Study Unit
RiflesBy
Carl P. Wood
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01/22/03
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About the Author
Carl P. Wood grew up on a farm in West Virginia where hunting was
a way of life. Given his first .22 rifle at 9 years of age and his first
shotgun at age 10, Carl began a love affair with guns and shooting.
After serving in the U.S. Navy during World War II, he married and
set about earning a Journeyman machinist’s card in a shop of the
old tradition. He spent countless hours as a disciple in the shop of
the late gun writer and ballistics expert Phil Sharpe. Later, he
worked directly for Richard S. Boutelle, then President of Fairchild
Aircraft, on several development phases of the AR–15 rifle. Just a
few of Carl’s writing credits include a stint as shotshell editor of the
American Reloading Association Bulletin, current gun editor of West
Virginia Woodsman, field editor of Backwoodsman, and editor of The
Bird Dog Review. Carl wrote The Gun Digest Book of Sporting Dogs,
and the shotshell reloading section of Dean Grennell’s ABC’s of
Reloading. Working with metallurgist Jim Kelly, Carl wrote a series
of articles on black powder pressures and barrel steels, which were
published in Muzzle Blasts. These controversial articles resulted in
changes in the steels used to manufacture muzzleloaders.
iii
In this unit, we'll address the complete rifle,
emphasizing design, function, repair, and
modification of different type actions.
Following a brief history of rifle development,
the unit considers the rifle barrel, thoroughly
discussing barrel types, steels, and their
applications. The barrel section also covers barrel attach-
ments and their purposes. The purpose of the section on
trigger mechan-isms is to alert you to the dangers of work-
ing on triggers and sears, and to open your eyes to possible
legal complications. The final function/troubleshooting
sections address lever, pump, bolt, semiautomatic, double-
barrel, and single-shot action rifles.
When you complete this study unit, you’ll be able to • Explain the history and development of rifles
• Identify the different types of rifle barrels in relation to theirapplications
• Identify the different barrel steels
• Describe methods of barrel manufacture and methods forrifling during the manufacturing process
• Explain how to fit a barrel blank to an action
• Summarize the purposes for and installation of barrelattachments
• Recognize the liability associated with trigger work
• Identify the eight major functions of various rifle actions
• Troubleshoot the various rifle actions and identify tools usedfor rifle repair
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HISTORY OF THE RIFLE 1
Freshening Out and Reboring 4The Caplock 7The Advent of Metallic Cartridges 7
PRINCIPLES OF RIFLING 9
Bullet Yaw 9Proof Testing 12Nodes of Vibration 13Gas Cutting 14Bore Erosion 14
BARRELS 17
Outside Barrel Diameter 18Barrel Styles 18Ultralights 18The Accuracy/Weight Tradeoff 22Installing Barrel Liners 26Rifling 29Lapping Shotgun Bores 38
BARREL STEELS 41
Black Powder, or Gun Barrel Grade, Carbon Steel 41Ordnance Steel 43Nickel Steel 44Stainless Steel 44Installing a Barrel on an Action 46Turning Down Barrels 52Barrel Straightening 52Recoil Compensators 53Flash Suppressors 56
TRIGGER MECHANISMS 58
Trigger Adjustment 59Removing Two-stage Triggers 61Aftermarket Triggers 62Set Triggers 63
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FIREARM FUNCTIONS 65
Troubleshooting 66Some Essential Tools 70Lever-actions: Function and Troubleshooting 72The Sequence of the Eight Functions in
Popular Lever-action Rifles 75How Lever-actions Lock Up 78Drawbacks of Lever-actions 78Troubleshooting Lever-actions 78
PUMP-ACTIONS: FUNCTION AND TROUBLESHOOTING 88
The Sequence of the Eight Functions in Pump-action (Slide-action) Rifles 88
How Pump-actions Lock Up 90Troubleshooting Pump-actions 90Bolt-action Rifles: Function and Troubleshooting 93How the Eight Basic Functions Apply in
Modern Bolt-action Rifles 95Lock-up Systems, Bolt-action Rifles 97Multiple Locking Systems 98Gas Venting, Bolt-action Rifles 99Safeties on Bolt-action Rifles 100Manufacturing Bolt-action Rifles 100Troubleshooting Bolt-action Rifles 101Semiautomatic Rifles 106Sequence of the Eight Functions in
Autoloading Rifles 112Troubleshooting Semiautomatic Rifles 113
DOUBLE RIFLES 118
Troubleshooting Double-barrel Rifles 120Single-shot Actions 120The Sequence of the Eight Functions in
Single-shot Rifles 124Troubleshooting Single-shot Rifles 125
SELF-CHECK ANSWERS 129
EXAMINATION 131
1
HISTORY OF THE RIFLE
Scholars generally agree that guns were first used in China
and that gunpowder was invented in China. However, they
differ as to where it was first used to propel missiles. The
general consensus is that gunpowder was first used as a
missile propellant in hand cannons made of bamboo stems
bound together by leather. Apparently, stones were seated
over a charge of powder inside a bamboo tube. Some type of
slow match through a touchhole ignited the charge (Figure 1).
Note: In your first module, you received A History of Firearms,
which comprehensively details all types of early firearms.
This section limits its historical discussion to rifles. Also,
function/troubleshooting sections appearing later in this unit
detail historical developments of various rifle action types.
While the Italians are generally credited with developing guns
in the early period, the development of the rifled barrel is
almost certainly a German invention. We believe the first
rifling had straight grooves running parallel to the axis of the
bore. Apparently, early German experimenters thought that
causing a projectile to follow a straight line inside the barrel
Rifles
FIGURE 1—This illustration depicts what a bamboo hand cannon might have looked like. The drawing is entirelyconjecture, as we know of no existing bamboo-barreled guns. Only sparse written description remains.
would cause it to continue doing so after exiting the barrel.
Evidently, there is some truth in this straight rifling idea.
One of America’s premier barrel makers, the late G. R.
Douglas of Charleston, WV, experimented with straight
rifling. He verified that straight grooved barrels did shoot
better than the smoothbore, but not as well as the same
groove pattern in a suitable spiral twist.
We’ll probably never know who concluded that spiraled rifling
would improve the accuracy of a projectile by stabilizing it
like a gyroscope or a spinning top. Indeed, we can’t even be
sure that accuracy wasn’t an unexpected side effect of an
experiment. The stories surrounding the invention of spiraled
rifling are many. In 1984 Mr. Gottfried Berger of Suhl,
Germany, shared a noteworthy one with me at a black pow-
der rendezvous where we had several long talks regarding
German and American black powder guns.
Gottfried’s story concerns an apprentice gunsmith in Suhl
who became angry with his master and spitefully twisted a
barrel already cut with straight rifling grooves. Realizing the
enormity of his offense, the apprentice hurriedly filed the
flats straight to hide his misdeed. As the story goes, this bar-
rel became famous for its accuracy. The master gunsmith
couldn’t duplicate the barrel’s performance. Only upon close
examination did he discover the spiral effect twisting had
given the rifling.
The story goes on about how the gunsmith made many more
of these accurate barrels and became famous. Apparently, he
kept the twisted rifling a secret for many years.
At first, this story seems unlikely. However, given the difficulty
of seeing down a bore that can’t be unbreeched without
removing the breech plug, and considering the absence
of modern bore scopes and lights, it becomes somewhat
believable.
In any event, it’s almost certain that rifling didn’t afford
much advantage until the wheel-lock became popular.
Apparently, the mechanics and slowness of the matchlock
system prevented the shooter from holding the gun steady
long enough to benefit from improved accuracy.
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The Snaphaunce further improved the shooter’s ability to
deliver a projectile to the aiming point with the enhanced
accuracy of the rifled barrel. Then, around A.D. 1620, the
flintlock afforded more precision to the process of aiming
and discharging a firearm. Finally, we reached the point
where an accurate barrel enabled greater precision.
The rifled flintlock reached its zenith in the so-called
Kentucky Rifle, which was actually the Pennsylvania rifle
that provided the settlers with superiority over the native
Americans. This same Pennsylvania Rifle used in Kentucky
reached its zenith during the settlement of Kentucky and
Ohio (1770–1790) and became known as the Kentucky Rifle.
In addition to the great strides made by American gunsmiths
during this period, German gunsmiths were perfecting their
Jaeger (pronounced Yager) rifle (Figure 2).
FIGURE 2—The upper rifle is a Kentucky-style recreation by Master Riflesmith Dave Kidwiler of GerrardstownW.V. The Jaeger rifle at the bottom is a recreation by Master Riflesmith Mike Small of Hedgesville, W.V. Both ofthese rifles are fine examples of the working rifles of the frontier era.
The Jaeger rifle was a relatively short-barreled (24–28 inch)
gun in heavy caliber (.50–.90). As produced by the better
German gunsmiths, these guns were heavily carved, inlaid,
filigreed, and engraved examples of the best of the gun
maker’s art. The Jaeger also had a relatively short, yet
heavy, stock as compared to the long, slender, graceful,
Kentucky rifles.
The Kentucky rifle barrel lengths ranged from a short 36
inches to 50 inches or longer. The stocks were also very
slender, almost to the point of fragility. Kentucky rifles were
of widely varying calibers with the majority in the .40 to
.50 caliber range in the mid to late 1700s. In the Eastern set-
tlements, following the disappearance of elk and bison and
the end of Indian fighting in the early 1800s, smaller calibers
were usually made. The .36 caliber is representative of newly
made guns used in settlements east of the Mississippi in the
latter half of the nineteenth century (Figure 3).
The high price of lead and powder also contributed to smaller
calibers. So, too, did the knowledge that shot-out bores could
be enlarged by “freshening” and “reboring,” therefore extend-
ing the firearm’s use.
Freshening Out and Reboring
Early rifles didn’t profit from the high-quality barrel steels
available today. Instead, they were formed from relatively soft
wrought iron. With each firing, the wrought iron suffered
moderate wear when the hot gases reacted with the surface
steel. Also, chemical reactions caused by burning sulfur in
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FIGURE 3—This .36 caliber halfstock is a recreation, by Carl Wood, of a late 1800s squirrel rifle made by D. Markerof Charles Town, WV. It’s as near to an exact copy as is humanly possible. To make the authentic copy, it was necessary to make the lock and furniture by hand.
Rifles 5
the powder helped erode the barrel. When sulfur dioxide
(SO2) absorbed water from the moisture (H2O) in the air, it
became sulfuric acid (H2SO4). The acid corroded the bore.
Eventually, bore wear affected barrel accuracy. When a rifle
became too inaccurate, the owner took it to a gunsmith for
“freshening out.” The gunsmith accomplished freshening out
by lightly reaming and lapping the top of the lands enough to
clean them up into a smooth surface like the original bore.
The lands are the tops of the raised rifling between the
grooves.
Figure 4 shows the form of rifling used in the M1917 Enfield.
Notice the five lands and the five grooves, which are of equal
width. The bore is .300 inch. The grooves are .005 inch deep.
Figure 5 shows the rifling of the Metford-type rifle, also used
in the Model 99 1939 7.7 mm Japanese rifle.
FIGURE 4—Lands and Groovesof the M1917 Enfield
FIGURE 5—Lands and Groovesof the Metford
The usual reaming removed .010 inch from the top of the
lands and resulted in a bore size .020 inch larger than the
original diameter (.010 inch off each side).
Note: The figures are approximate, as most gunsmiths of the
era lacked precision measuring equipment to measure incre-
ments of .001 inch. They just reamed and polished the barrel
until it regained a smooth, regular surface.
Sometimes the bore was in such poor condition that it
required more than .010 inch to clean up the lands. In such
cases, the gunsmith would rebore the barrel to restore the
smooth track along which the ball passed and thus restore
accuracy.
Reaming the tops of the lands increased the rifle’s caliber. In
such cases, the gunsmith made a new bullet mold to fit the
larger land diameter of the barrel (Figure 6).
Freshening out resulted in many different calibers, as each
freshening usually resulted in a two-caliber increase. A cal-
iber is .01 inch, so a .40 caliber muzzle-loading rifle has a
land diameter of .400 inch. A rifle that was originally a
.40 caliber and had been freshened twice would likely be
about .44 caliber. (We measure modern rifle barrel bores
differently.)
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FIGURE 6—Drawing of the Pilot Reamer used to “freshen” muzzle-loading barrels starting in the mid-eighteenth century. Gunsmiths made earlier reamers by inserting a steel cutter in a wooden rod. Thewooden type wasn’t very accurate and required a lot of hand lapping to attain an even surface.
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Usually, rifle barrel grooves could be freshened out twice
before requiring reboring. During the reboring process, the
gunsmith dug all rifling out of the barrel. Then, the gunsmith
would cut new rifling, just as when making a new barrel.
Next, the gunsmith repeated the freshening out and reboring
processes until the bore required too large a ball-and-powder
charge for the rifle owner’s purposes, or until the walls of the
barrel became too thin to recut the rifling. At this point, the
gunsmith would usually bore out the rifling and make the
gun into a smoothbore. The shooter could then use the
smoothbore as both a rifle and shotgun, depending upon
whether it was loaded with shot or ball. Sometimes such guns
were loaded with both shot and ball. Such loadings, known
as “Buck & Ball” loads, were the standard loadings of such
early American Colonial troops such as Roger’s Rangers.
The Caplock
The advent of the Caplock further enhanced rifle accuracy by
enabling much faster and dependable ignition. The Caplock
used a copper cup filled with fulminate of mercury. The cup
was set over a small nipple leading into the powder charge.
When the strike of the hammer exploded this cup, it immedi-
ately ignited the black powder charge, thus firing the rifle.
Importantly, the caplock was far more dependable than the
flintlock in unfavorable weather conditions (rain and snow).
The Advent of Metallic Cartridges
The next development of significance to rifled barrels was
cartridges. While the Ferguson and Hall rifles worked fairly
well, it wasn’t until the appearance of the metallic cartridge
that really significant advances in rifles occurred. The metal-
lic cartridge offers an efficient method of sealing the breech
on an open-breech rifle. During firing, the pressure of the
exploding powder gases expands the case against the walls
of the chamber.
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Self-Check 1
At the end of each section of Rifles, you’ll be asked to pause and check your understanding of what you have just read by completing a “Self-Check” exercise. Answering these questionswill help you review what you’ve studied so far. Please complete Self-Check 1 now.
Indicate whether the following statements are True or False.
_____ 1. The Jaeger rifle was a slender, graceful gun.
_____ 2. Matchlock was the first ignition system that allowed careful shot placement.
_____ 3. Reboring is the removal of the worn rifling and cutting new grooves in a worn barrel.
_____ 4. A caliber is .02 inch.
_____ 5. Kentucky Rifles had barrel lengths as long as 36″ to 50″.
Check your answers with those on page 129.
Rifles 9
PRINCIPLES OF RIFLING
Bullet Yaw
In this section, we’ll introduce some highly important factors
that determine a rifle’s accuracy. The student studying rifling
and the principles that govern rifle performance should
understand bullet yaw and nodes of vibration.
Bullet yaw is an offspring of the Coriolis effect, which causes
water to form a whirlpool as it goes down a drain and a toy
top to travel in a circle as it spins. Bullet yaw causes a bullet
to travel around the axis of its flight in a spiral pattern. If
you envision a straight line, which we’ll call the “true bullet
path,” the effect of yaw is to make the bullet travel in a spiral
course around this true path. This effect is entirely different
from, but a side effect of, the bullet spin imparted by the
rifling (Figure 7).
The bullet yaws at a much slower rate than it spins. For
example, suppose you fire a bullet from a barrel having a
rifling twist rate of 1 inch in 12 inches, which is a fairly com-
mon twist rate in modern rifles. The bullet spins at the rate
of one turn for every foot of forward travel. This may seem
like a fairly slow rotation until you consider that a bullet
from a 1-in-12 pitch barrel traveling at 3,200 feet per second
(fps) travels 100 yards in .097 seconds. It spins 300 turns in
.097 seconds, which we’ll round off to .1 second to simplify
matters. Therefore, by multiplying 300 turns in .1 second by
10 to approximate how many times it spins in one full second,
you come up with about 3,000 revolutions per second (rps).
FIGURE 7—As a bullet yaws, it spirals around the axis of its true line of flight.
Rifles
Furthermore, multiply 3,000 rps by 60 seconds to approxi-
mate how many times it spins in one minute. The result is a
rotational rate of 180,000 revolutions per minute (rpm),
indeed a high rotational rate. It’s common for improperly
constructed bullets to vaporize in flight by such ultrahigh
rotational rates. I demonstrate this effect at gunsmithing
seminars in the following way. I use a Remington model 721
magnum action, probably the strongest action ever sold as
an “over the counter” item. The gun was chambered for the
.300 Weatherby cartridge. I loaded it with the 100 grain
Speer “Plinker” bullet. It shot well over SAAMI (Sporting Arms
and Ammunition Manufacturers Institute) specifications—
a charge of H414 powder for a bullet velocity, measured with
a chronograph, as 4,400 fps.
When fired at a 40 inch, square-shotgun pattern sheet at
30 yards, the 100 grain Speer, traveling at 4,400 fps, causes
a ragged-edge, 8 to 10 inch hole in the center of the paper.
Also, a spattering of tiny pinholes surrounds the paper.
Occasionally, there will be a crescent-shaped hole in the
paper where the thoroughly flattened bullet jacket went
through the paper. This is no fault of the bullet, as it was
designed to be fired at velocities of 2,000 fps or less. It sim-
ply isn’t capable of withstanding the terrific centrifugal forces
generated by the rotational velocity of such a loading, which
travels 100 yards in .076 seconds. Using the same method as
before, and allowing for the faster barrel twist of the .300
Weatherby, we arrive at a rotation of 225,000 rpm (Figure 8).
Warning: Overloading ammunition can prove fatal! Never exceed
manufacturer specifications when hand-loading ammunition.
Throughout this document, I provide facts about overload,
which pertain to clearly unsafe practices and to illustrate the
effect of excessive spin on a particular bullet. I have worked
with chronographs, pressure barrels, proof guns, and similar
experimental equipment for many years as part of a business
that researches and develops new loadings for both metallic
and shotshell ammunition. Obviously, someone must make
the first loading of experimental ammunition. Only someone
with many years of experience should make such experimen-
tal loadings, and under carefully controlled conditions. When
I make a loading, such as the high-velocity .300 Weatherby
round, I use my experience and judgment to predict the
10
Rifles 11
outcome. I base my hypothesis on much education and
research. Even then, the first firings of such loadings will be
in a pressure barrel in an enclosed firing chamber under
stringent safety procedures.
Warning: Education Direct has no control over experiments
that a student may conduct. Because it’s unlikely a student
can match Mr. Wood’s experience, we advise in the strongest
terms that you don’t assemble any hand load, including so-
called “Blue Pills” or “Proof Loads,” which exceed industry
standards. We disclaim any responsibility if you disregard
this warning.
When you must test the safety of a loading, there’s a safe, yet
less desirable, method of testing. Tie a rifle in an old automo-
bile tire for test-firing purposes. With this method, the stock
is inside the rim of the tire and the forend tied down onto the
tire. You fire the gun by pulling the trigger with a string from
a safe distance (Figure 9).
FIGURE 8—A 110 grain bulletleft this 2 1/2 inch hole in apiece of cardboard when overloaded with the samecharge just described. In thisinstance, the target was penetrated just 15 yards fromthe muzzle. Notice the tinypinholes, which indicate thatthe bullet is breaking up.
Proof Testing
Where no proper facilities are available for test-firing, the
practice, known as proof testing, is to fire a load with a 20
percent increase in the powder charge usually used in the
rifle. Then, carefully examine both the rifle and fired cartridge
for signs of excess pressure. Assuming that upon careful
inspection the gun and fired case show no signs of trouble,
some people believe the gun may be fired using a charge 20
percent less than the proof load. WE DO NOT RECOMMEND
THIS PRACTICE. After you determine the resultant pres-
sures, you decide whether the loading is safe for use in a
particular gun. In the instance just discussed, we decided
that the load would be safe to fire in only the strongest
actions such as the Remington 721 and Fahrquahr actions.
Warning: Most progressive-burning smokeless powder ignites
at a rate proportional to the pressure within the bore. If the
pressure is too low, the powder may not burn before the bul-
let exits the barrel. If it’s too high, the powder may detonate
(explode rather than burn). Ammunition companies specially
load proof loads used in factories using powder and powder
charges carefully developed with safety in mind to create a
specific pressure level in the bore. Simply increasing the
charge 20 percent, as previously mentioned, is meaningless
unless the necessary equipment is available to determine
exactly what pressures are being generated. Also, even if a
rifle reveals no apparent damage after firing a proof load(s),
it still may not be safe. Even though it hasn’t blown up, the
stressed material in it may yield some. The result can be
anything from excessive headspace because the action
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FIGURE 9—This photo depictsa muzzle-loading rifle mountedin a tire for test-firing purposes.The tire cushions the recoil.Note that you should neverfire a rifle from solid mounts,as the recoil will likely breakthe stock.
Rifles 13
stretched, to an undetected crack in the locking lug or some
other part. Proof testing is dangerous work. You should refer
all proof testing to an independent laboratory set up specifi-
cally for this purpose.
Nodes of Vibration
Another factor in rifle performance, or accuracy, is barrel
vibration. When a gun fires, the effect of the sharp explosion
is similar to what happens if you strike a hard blow to a
metal barrel with a hammer—it vibrates. The vibrations
cause the barrel to bend slightly as the shock waves from the
explosion travel along its length. (The effect is similar to the
waves caused by throwing an object into a pond.)
The waves of vibration travel up the gun barrel and cause its
muzzle to wave back and forth. The waves, known as nodes
of vibration, are the bane of accuracy. Understandably, the
muzzle waving back and forth from the effect of the vibration
affects accuracy by the point in the barrel’s swing at which
the bullet exits. Sometimes a hand loader can develop a load
that causes the bullet to exit the muzzle at the center of the
node of vibration. This greatly improves accuracy, as the
muzzle is at a pivot point (Figure 10).
FIGURE 10—This drawing depicts nodes of vibration. The most accurate load is the one that exits thebarrel at the node instead of at the overtone of swing.
Extreme internal pressures generated when you fire a mod-
ern rifle cause the bore surface to become superheated,
which can also affect accuracy. The first few layers of mole-
cules of the surface steel actually melt. Eventually, depend-
ing on how heavily the shooter uses the rifle, the slow
removal of surface metal inside the bore significantly con-
tributes to barrel wear. The major causes of barrel wear are
gas cutting and erosion ahead of the chamber caused by the
high-speed passage of partly burned particles of powder.
Note: Internal bore conditions are very important to accuracy
in a rifle. Allowing a barrel to rust from lack of cleaning ruins
a good barrel. We’ll discuss more about cleaning later.
Gas Cutting
Powder gases leaking past the bullet cause gas cutting. The
powder gases subject the inner barrel surface, where they
pass between the bullet and bore, to high-pressure friction
and cutting. You can best counter gas cutting by using prop-
erly sized, well-made bullets.
Bore Erosion
Bore erosion, just ahead of the chamber, is caused by the
friction of burning powder particles. The particles subject the
area to extreme abrasive action during the few nanoseconds
that the bore surface melts, or at least softens. The extreme
heat generated by burning powder under high pressure melts
the bore surface.
You can greatly lessen bore erosion by using lighter-than-
maximum loads. Some calibers, which use large amounts of
powder in a relatively small bore, erode their barrels much
faster than less-powerful calibers. Cartridges, such as the
.220 Swift, .300 Weatherby, .280 Remington, and other
“overbore” calibers, are especially bad at eroding bores.
No reason exists to use maximum loads in most overbore cal-
ibers for hunting or target shooting. When loaded down to
acceptable pressures, such calibers won’t erode barrels any
faster than lower-powered calibers.
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Note: Many believe that single-base powders cause more
erosion than double-base powders.
You can best detect bore erosion by looking through the
clean barrel from the breech end, when possible, and closely
examining the area just ahead of the chamber for smoky,
dark-appearing sections. Severe bore erosion is evident when
the rifling ahead of the chamber seems to be worn away for
some distance. If, when you look through the breech end, the
barrel exhibits wear to about six inches ahead of the chamber,
heavy erosion has taken place, which severely diminishes
accuracy.
In such an instance, if high accuracy is required, the only
recourse is to replace the barrel, or to install a barrel liner.
Personally, barrel liners I’ve used have never provided top-
notch accuracy. I consider five shot groups of less than an
inch at 100 yards to be top accuracy. Still, some folks tell me
they get excellent accuracy from barrel liners.
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Self-Check 2
Fill in the blanks in the following statements.
1. Gunsmith’s should _______ make experimental loadings for which they have no test data.
2. You replace a rifle barrel when the effects of erosion won’t meet the _______ needs ofthe owner.
3. The major causes of barrel erosion are _______ by powder particles and gas cutting.
4. The seemingly insignificant change of a few grains of powder sometimes results in greatly_______ of the barrel vibration.
5. Powder gases leaking past the bullet cause _______.
Check your answers with those on page 129.
Rifles 17
BARRELS
While barrel manufacturing is beyond the scope of this
study unit, you should know enough about barrels to identify
them and make recommendations to customers based on
prospective use.
Since barrels are manufactured for different purposes, many
styles are available. The ordinary modern rifle barrel is some-
where between .17 and .45 caliber. Lengths will vary from
18 inches for a carbine-style rifle to 26 inches for a heavy
caliber designed for maximum velocity from overbore car-
tridges and loads. Twenty-six inches is the maximum practi-
cal barrel length. Rarely will a modern rifle barrel be over
26 inches long. Modern smokeless powder burns a normal
charge within about 22 inches of bore length, and most car-
tridges develop their major velocity potential within 24 inches
(Figure 11).
As modern shooters appear willing to sacrifice a little velocity
for a lighter, easier-handling rifle, the latest trend seems to
lean toward the shorter 22 inch barrels. Still, probably more
24 inch barrels are being manufactured for centerfire rifles
today than all other barrel lengths combined. It’s possible,
for example, to develop more velocity in a .30/06 shooting a
150 grain load in a 26 inch barrel. However, the increased
velocity afforded by the extra 2 inches is only about 110 fps
(depending on the burning rate of the powder being used).
Such an increase is not sufficient to warrant the additional
weight and cumbersome handling of the longer barrel.
Conversely, in overbore cartridges such as the .300
Weatherby, the additional velocity afforded by a 26 inch
barrel is about 250 fps (again depending on the burn rate
of the powder). A velocity of 250 fps is often considered
enough gain to justify the additional length.
FIGURE 11—Illustration of a Barrel
Outside Barrel Diameter
To some extent, we determine the outside barrel diameter by
bore diameter, as safety requires sufficient wall thickness.
Another important consideration is prospective use. Generally,
the action the barrel must fit determines its rear diameter.
Still, in many instances, we determine barrel diameter by
whatever bar stock of barrel steel is available at the best
price.
Barrel Styles
Often, the finished barrel diameter bears little relationship
to the original bar stock. All types of tapers and turnings can
be made to suit customers’ or barrel makers’ designs. Barrels
range from slim ultralight styles thinned down as far as safe-
ty considerations will allow, to heavy 30 to 40 pound “bull”
barrels that have larger diameters than the receiver rings
they install on. Myriad contours and dimensions fall between
such extremes.
Ultralights
Hunters carry the ultralight-style barrel in extreme condi-
tions such as the steep terrain encountered while mountain
hunting for sheep and goats. In such environs, every ounce
saved in rifle weight is like a pound by day’s end. Great care
must be taken in trimming off barrel weight through reduced
diameter. Back in the days before the Sporting Arms &
Ammunition Manufacturer’s Institute (SAAMI) introduced
specs, instances occurred where barrels were “turned” a little
too thin to reduce weight. The results were bulged and even
blown chambers!
Note: The purpose of the Sporting Arms & Ammunition
Manufacturer’s Institute (SAAMI) is to furnish standards to
which all American manufactured arms and ammunition
could comply. SAAMI specifications replaced the formerly
chaotic manufacturing tolerances of the arms industry,
which varied according to each maker’s preference. SAAMI
has been a boon to all who work with firearms.
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Often, ultralight barrels suffer from relatively poor accuracy
due to “barrel whip.” Barrel whip, caused by insufficient
barrel stiffness, greatly exaggerates the effects of nodes of
vibration.
Featherweights
Next up the scale of barrel stiffness from ultralights is the
featherweight barrel. This type is somewhat heavier in the
chamber area and the contour just ahead of the chamber. By
allowing more metal to remain in this critical area, the barrel
maker provides two major advantages. First, and of prime
importance, is the additional strength in the chamber area,
which becomes critical in case of overload.
Note: Other factors contributing to increased chamber
pressures include
• Improperly seated bullets
• Cases “stretched” by reloading and resizing that haven’t
been correctly trimmed
• Improper crimping
• Unusually thick brass that has less powder capacity
• Hot “magnum” primers used with an easily ignited
powder
• Rusted or obstructed bores
• Firing under unusually high temperatures
The second advantage of allowing more metal to remain is
the additional stiffness this relatively small increase in barrel
weight affords. A slender barrel will vibrate more and faster
than a larger diameter barrel, given the same impetus. A
slight weight increase in the chamber area often provides the
potential for higher accuracy.
Light Hunting Barrels
The next heavier barrel type is often called a “Light Hunting”
weight barrel, although various manufacturers have their
own pet names for such barrels. There’s considerable dispar-
ity of design in this barrel category. Some makers believe
that a fast taper is the best answer to the vibration problem.
A barrel made following this school of thought tapers rapidly
from just ahead of the chamber area to a point about one
third the distance to the muzzle. It then changes to a very
slow taper for the last two thirds of the muzzle end.
Another school of thought professes that a straight taper
from the area just ahead of the chamber to the muzzle
affords more stiffness and accuracy. This belief leads to a
somewhat heavier barrel on a light hunting rifle, but does
seem to produce very accurate barrels in the lighter weights.
Standard Weight Barrels
Most factory sporters (standard hunting rifles) use the stan-
dard weight barrel.
Light Varmint Barrels
Next up in weight is the light varmint weight barrel. It’s
heavier than the light hunting barrel but lighter than
barrels such as those on the Remington Model 700
Varmint Specials (Figure 12).
Varmint Special Barrels
The varmint special is one of the most successful over-the-
counter designs available today. It produces remarkable
accuracy. Mine consistently produces 200 yard groups of less
than an inch diameter with carefully developed hand loads
and match-grade bullets.
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FIGURE 12—This Remington “Varmint Special,” mounted with a 4 �� 12 Redfield Ultimate Illuminator sitting atopa shooting rest, is the ultimate varmint shooting setup. This rifle is capable of one inch groups at 200 yards.
Rifles 21
Heavy Varmint Barrels
Next in weight and stiffness are the heavy varmint barrels,
often weighing in excess of 14 pounds. To my way of think-
ing, they don’t produce enough improvement in accuracy to
justify their uncomfortable and awkward weight. However,
with careful and extensive experimentation and many differ-
ent powder loadings, charge weights, and bullet and case
combinations, you can obtain an accuracy level greater than
most of us can shoot under field conditions.
Bench Rest Barrels
Bench rest guns use the heaviest barrels. It really is necessary
to fire guns with “bull barrels” off benches, as many bench
rest rifles weigh as much as 40 pounds. No one can shoot
them effectively in handheld positions. From the bench, these
massive bench rest barrels are most accurate at extended
ranges. They are stiffer, and the sheer static energy resulting
from their weight largely nullifies the effect of barrel vibrations.
Discussion of bench rest barrels brings an interesting story
to mind. In an effort to fire even tighter groups, bench rest
shooters are forever experimenting with bedding methods
and barrel mounting. Back in the early 1950s when Dubois,
PA hosted the bench rest championships, some shooters
successfully bedded barrels in Silly Putty, which is literally a
slow liquid. Yes, I’m referring to the same substance sold as
a children’s toy—the stuff that slowly creeps into the tiniest
of crevices. Silly Putty has some interesting properties. If you
leave a ball of it on a table for several hours, it will end up as
flat as a pond’s surface. At normal temperatures, it won’t
move or flow rapidly under any circumstances. When frozen,
if you strike it with a hammer, it shatters like glass. Form it
into the shape of a stick, and if you try to bend it rapidly it
breaks. Bend it slowly, though, and it will assume any
shape. Lay pieces of it together for a few hours and it will
flow into one solid mass again.
The properties of Silly Putty help illustrate just how impor-
tant a rifle’s bedding is to performance. Naturally, using Silly
Putty as a bedding material is impractical because unless the
rifle stays in a flat and level position, the putty will flow out in
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a few hours. In the spirit of enhanced accuracy, we chiseled
out an oversize channel for the barrel in a stock. This allowed
no wood-to-metal contact except at the bottom of the action
where it mounts with screws to the stock. Then, we slowly
filled the space between the stock and barrel with Silly Putty.
When we fired the gun, the putty acted as a solid bedding for
the barrel with absolutely no stress or uneven pressure on
the barrel at any point. This resulted in some really good
groups and proved that a barrel must be perfectly bedded
to achieve its maximum accuracy potential.
Still on the subject of bedding, the practice of “floating” a
barrel seems to be the most popular bedding method used
today. A rifle has a properly floated barrel if you can pass a
dollar bill freely between the stock and the barrel all the way
down the forend until it reaches the receiver ring, which
should be resting solidly on the stock. Floating avoids
changes in the impact point due to stock movement from
both temperature and humidity changes.
The new fiberglass or graphite stocks, with the barrel firmly
bedded in epoxy, are claimed to eliminate all movement of
point-of-impact due to temperature and humidity changes.
It seems as if they do, to a large extent, eliminate “zero”
changes. They also greatly reduce weight and are seemingly
stronger than wood. Many shooters prefer them, and I have
no quarrel with those who do. Their disadvantage is that
they’re cold to the touch in winter, and for me, a camouflage
plastic stock will never equal the beauty of a piece of fine
wood.
The Accuracy/Weight Tradeoff
Getting back to barrels, there’s a definite tradeoff between
accuracy and lighter barrel weight. The point at which light-
weight barrels start to severely handicap accuracy varies
inversely with the caliber and power of the loadings. A barrel
chambered for a .22 long rifle will likely be more accurate
than the same barrel profile and weight chambered for a
.22 WRF Magnum, and certainly more accurate than if
chambered for a .22–250 Remington. I have a Winchester
Model 52 Sporter, made in the 1940s, which will shoot .260
inch diameter five-shot groups at 50 yards using Eley “Black”
22
Rifles 23
target ammunition. I recently acquired a Ruger M77/22
Magnum chambered for the .22 Winchester Magnum Rimfire
that consistently shoots .500 diameter 100 yard five-shot
groups with RWS FMJ match ammunition. This little rifle
has shot 100 yard groups as small as .170 inch over bullet
diameter. So, it’s possible to achieve high accuracy from
lightweight barrels in low-powered loadings. When we try to
use heavy loads in light barrels, though, the vibration upon
firing destroys accuracy (Figure 13).
A barrel’s diameter and stiffness are important in obtaining
accuracy, as is its weight. I demonstrated this back in the
1950s while working for Fairchild’s Armalite division on the
development of the AR-15.This rifle later became the Army’s
M-16 standard-issue rifle. One of the problems we addressed
was excessive rifle weight. Every ounce of rifle weight is an
ounce of ammunition weight a soldier can’t carry due to lim-
its on just how much weight the average man or woman can
carry. Naturally, the objective was to design the lightest pos-
sible rifle that would meet service weapon requirements.
One of the ideas we tried concerned reducing weight by using
a Dural (aircraft grade Duraluminum) barrel with a stainless
steel liner. Although I can’t recall the exact figures many
years later, the Dural barrel weighed much less than the
FIGURE 13—This Ruger M77/.22 Caliber Winchester RF Magnum is a highly accurate 150 yard varmint andsquirrel rifle. It’s one of the most accurate rifles I have ever shot.
steel barrel. Deflection tests proved it to be nearly as stiff as
the steel barrels we had been using, and we expected great
things from this promising design. A lack of accuracy soon
dampened our enthusiasm. The rifle was chambered for the
.222 Special cartridge furnished by Remington, which later,
with slight modifications, became the .223 military round
used in the AR-15 and M-16 military rifles (Figure 14). We
had averaged two inch groups at 100 yards with a steel
barrel. However, the Dural/steel barrel opened up 100 yard
groups to around six inches or more, which the military
service didn’t accept as an accurate weapon.
Armalite also tried making an even larger diameter barrel,
which was stiffer than the steel barrel but still weighed only
about half as much. Although this improved accuracy some-
what, it still wasn’t acceptable. I was convinced that the
accuracy problem was the lack of weight. I determined this to
be true by turning down one of the inaccurate Dural barrels
on a lathe and making a lead sleeve that I installed on the
barrel to duplicate the weight of the steel barrel. This lead-
sleeved barrel wasn’t nearly as stiff as the steel barrel, but it
shot nearly as well, giving groups on the order of 2 inches at
100 yards.
Giving up on the Dural military barrel, Armalite, under the
“S-F Industries” (Sherman Fairchild) name, tried to sell a
Dural-barreled rifle built on a Remington bolt-action. It was
chambered for the .30 NATO (.308 WIN.) to meet the need for
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FIGURE 14—This is a box ofthe first lot of .22 caliberammunition made for themilitary. With slight modifica-
tion, this round became the.223 NATO round. This is oneof only a very few survivingboxes of this round—a collec-tor’s dream.
Rifles 25
an extremely light rifle, known as the Para-sniper, for moun-
tain hunters. Once again, the accuracy was just too poor.
I had a Para-sniper for about six months trying to get it to
shoot accurately. Even with very light loads that pushed a
120 grain bullet at only .30-30 velocity (2,300 fps), 100 yard
five shot groups were at best four to five inches. When the
velocity was brought up to standard .308 velocity (2,800 fps
with a 150 grain bullet), five shot groups opened up to
around 8 inches at 100 yards (Figure 15).
The experiences we just discussed convinced me beyond
doubt that weight, serving in the role of static energy, plays
a large part in the accuracy of a rifle barrel. This leads me
to conclude that we can only obtain optimum accuracy from
a barrel that’s both stiff and fairly heavy.
FIGURE 15—Shown is an advertisement for the S-F aluminum barreled rifle. Only a few such rifles were made.
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Installing Barrel Liners
Only those who have acquired sufficient hands-on experience
with the proper metalworking tools should attempt to install
barrel liners. Most barrel liners come with complete and spe-
cific installation instructions. Still, the following procedures
contain hints that can prove helpful if you decide to perform
the task. The first procedure—a head and shrink process—is
the same that we used to install the stainless steel liner in
the Dural barrel during the AR-1 project.
To install a .30 caliber stainless steel liner inside a barrel,
first grind the stainless liner on a Landis Centerless Grinder
to an outside diameter of .362 inch. Next, carefully bore
the barrel to an inside diameter of .360 inch. Tolerances are
+/–.0004 inch on the liner outside diameter and +/–.0008
inch in the barrel (inside diameter). This provides an interfer-
ence fit of .3624–.3592 inch on maximum and .3616–.3608
inch on minimum, so you have .0032 inch maximum to
.0008 inch minimum interference fit. Such tolerances are
as close as you can reasonably hope for and a lot closer
than those used in most gunsmithing shops.
Heat the bored barrel in a furnace, oven, or other heat
source to about 300° F.
Caution: Do not heat above 300° F, as overheating might
weaken heat-treated barrels.
Place the liner in a freezer set to the lowest possible tempera-
ture. Usually, 0° F will suffice.
Place the heated barrel in a secure position, and wipe a tiny
bit of high-temperature oil on the end of the cold liner before
rapidly driving it in.
Caution: Drive the liner in before it has time to warm and
expand. Do the job right the first time, as once the barrel
cools and the liner expands, they’re fixed in place for all time.
Many gunsmiths get into trouble installing liners as just
described because their machinery isn’t accurate enough for
this type of installation. A barrel liner installed in this man-
ner becomes an integral part of the barrel. The only way to
remove it is to bore it out, which is as it should be. It’s the
only method that you can depend on to produce acceptable
accuracy.
26
Rifles 27
Note: The only way to improve upon this type of liner instal-
lation is to pull a carbide burnishing button ground, fur-
nished by the liner maker, through the barrel to burnish the
surface for longer wear. This also brings the bore diameter
back up to bore nominal size after liner installation. Where
the interference fit was on maximum (liner at the top of the
tolerance and barrel bore at the minimum size), the bore
diameter could reduce enough to cause slight pressure
increases in a heavy-walled barrel.
Tinning
Another method of installing barrel liners is by boring the
barrel out to a diameter that produces a bore about .002
over the diameter of the liner. The liner is “tinned” (coated
with solder) and the rebored barrel inside diameter thorough-
ly cleaned and also tinned as well as possible. It’s not easy to
get a good tinning job throughout the length of the barrel
inside a small diameter hole. Do as good a job as possible
and use plenty of soldering flux. If the liner is completely
tinned, it will carry enough solder with it to fill the voids.
Caution: The diameters of the bore and liner must be within
a couple thousandths of an inch. If more clearance exists,
the solder won’t fill all the voids between the barrel and liner.
When you fire the gun, the thin walls of the liner may
expand to fill any voids. This will result in an uneven bore
diameter and adversely affect accuracy.
Prior to tinning the liner, place a small amount of high-
temperature grease or welding Spatter Guard inside each
end of the liner’s rifled bore to prevent solder from creeping
inside the bore. It’s almost impossible to remove solder from
the inside of a bore without causing damage.
Note: In the event solder somehow manages to get inside the
liner, the best removal method is to melt it out and wipe the
bore with an oily rag while it’s still hot.
After having tinned both the liner and the rebored barrel,
heat them both above the melting point of the solder. Then,
hold the barrel securely while you tap the tinned liner into
the hole in the barrel. I use an old vise and heat the jaws of
the vise to a dull red with a torch so a section of the barrel
doesn’t cool before I seat the liner.
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Note: It’s almost impossible to perform this type of liner
installation without having an assistant nearby. While you
work on one part—either the barrel or liner—the assistant
keeps the other one hot. One person just doesn’t have
enough hands.
Warning: This type of liner installation is very dangerous. The
barrel and liner are hot, and solder spatters off the liner as
you tap it into place. Furthermore, you’re working with a
hot vise. Always use heavy gloves and good safety glasses
(the type that covers the sides of your eyes) with safety
lenses thick enough to be safe if hit by hot solder. Above
all, use good sense and be careful.
The Epoxy Method
A third method of installing barrel liners begins by boring the
barrel in the manner described for soldering. Then, instead
of soldering the liner into place, use a slow-setting epoxy glue
to hold the liner in place. I haven’t personally obtained good
results from this method, but I have heard good reports from
several gun shops that epoxy liners in.
The epoxy glue’s lack of hardness troubles me. It seems as if
the pressure of firing would crush the glue to powder unless
I used a heavy-walled barrel liner. To verify my suspicions,
I ran a hardness test. A good modern steel barrel has a
Rockwell “C” scale hardness on the order of 30 Rockwell. A
wrought iron muzzleloader barrel has a hardness of about
20 on the same scale. When I ran a Rockwell test on some
epoxy advertised as suitable for installing barrel liners, I had
to go to another Rockwell scale to get a reading at all. There
were indications that the glue was around 2 on the C scale,
but it crushed and the reading was not reliable. Obviously,
the test did little to relieve my suspicions concerning the
epoxy method.
Final Thoughts on Barrel Liners
You shouldn’t use barrel liners in barrels chambered for
“Bottleneck” cartridges. You can use barrel liners for .22
Rimfires, straight-sided black powder cartridges, and muzzle-
loading rifles. A competent barrel liner installer can add
considerably to his or her business installing barrel liners in
28
Rifles 29
shot-out muzzle-loading rifle barrels. With the increasing
popularity of muzzleloader deer seasons and the general
muzzle-loading craze, a lot of folks are dragging Grandpap’s
old “smoke pole” out of the attic and relining or recutting it
for safe use.
As noted earlier, I never personally had barrel liners deliver
accuracy of less than one inch groups at 100 yards. The
ones that delivered the best accuracy were installed by the
heat-and-shrink process.
Rifling
Hand Rifling
Until well after the Civil War era, gun makers made rifled
barrels by hand cutting the rifling. In this process, a rifling
rod pulls a rifling cutter through the barrel. A rifling guide
turned in spiral grooves by a “rifling master” (or pattern)
guides the rifling rod in a spiral rotation. As the cutter is
pulled along, it rotates in the pattern set by the rifling master.
Note: The rifling master’s index plate has a hole for each bar-
rel groove; that is, a rifling master index plate for a six-groove
barrel has six index holes.
The “hook cutter” is usually pulled through the barrel a pre-
determined number of full passes through each rifling groove.
Four passes in each index position is a good average. For
example, after the cutter is pulled four full passes through
the barrel with the rifling master set to the first index hole, it
is run out the breech end to clear the rifling. Then, the index
pin is moved one hole clockwise in the rifling master, and oil
is squirted into the next groove before seating the cutter in it.
The cutter is once again pulled through the barrel four times.
After the cutter is pulled through the same number of
strokes in each index hole, it’s run out the breech end of the
barrel. Then the adjustment wedge or screw is moved to seat
the cutter about .002 inch deeper.
Note: If the rifling machine uses a steel cutter rod having a
screw-adjustable cutter with less free movement and “spring,”
it might be advisable to set the cutter up only .001 inch.
With experience, the operator learns to “feel” the proper
amount of cutter depth increase to set.
One of the most important factors in good rifling is absolute
uniformity in the passes of the cutter through the bore. After
“setting up,” the first pass in each groove will seem to pull
pretty hard if the cutter is properly sharp and cutting well.
It may not feel as if it’s cutting much on the final pass. The
operator shouldn’t be influenced by this seeming lack of cut-
ting and skip the last pass in an index hole, as the last pass
generally smoothes out some chatter marks from previous
passes. The cutting process continues until the rifling grooves
are of desired depth. Currently, most barrels cut by the hand
rifling process are used as muzzle-loading rifle barrels.
After hand cutting the rifling in a barrel, it’s necessary to
lap the barrel using a lead lap and abrasive polishing com-
pounds. We’ll discuss this process after considering other
rifling methods.
Barrel making is beyond the scope of this course. Therefore,
we intended the previous explanation of handcutting rifle
barrels to instill an appreciation for the work of those who
have brought the art to its present state. Following the given
instructions will enable you to make a hand-cut barrel only
if you have access to a rifling machine, or “bench.”
Broaching
Broaching is another method of barrel rifling. During
broaching, a broach is attached to a steel rod and pulled
hydraulically through the barrel as copious amounts of oil
are pumped through it. The oil serves as a lubricant as well
as carrying out the chips from the cutters.
The broach has several cutters, one for each barrel groove.
Each cutter somewhat resembles a short section of a saw
blade. It has several “teeth” or cutting edges, each about
.001 larger than the cutter ahead of it.
Broaching was the rifling method used for the large majority
of barrels made since 1910, and we still commonly use it.
The process is faster than hand rifling, producing a finished
barrel with one pass of the rifling head.
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Rifles 31
The highest grade broach-rifled barrels are finished by
pulling a carbide “burnishing tool” through them after the
broach operation. About .0005 inch greater in diameter than
the rifling broach, this tool has no cutting edges. After lubri-
cating the burnishing tool with grease, you pull it through
the barrel to smooth and compress the bore surface and
rifling by friction. The friction compresses the bore’s mole-
cules of surface steel, which increases strength. A burnished
bore will last longer and, unless it suffers some unusual
imperfection, there’s no need to lap it.
Hammer Forging
The most modern and, in most instances, best method of
rifling, is hammer forging. In preparation for hammer forging,
a carefully ground and polished male core rod, known as a
“mandrel,” is made to the exact size and shape of the fin-
ished rifled bore. The rifling grooves are raised spiral ridges,
and the lands of the bore are depressions between the rifling
grooves.
During the process, the mandrel is inserted into a barrel
blank rough bored just large enough to accept it. Then the
barrel passes through a machine where many automatic
hammers pound it down tightly on the mandrel until it
assumes the shape of the rod with the rifling on it. This
hammering to reduced size compresses the barrel steel and
makes a very fine and tough surface on the inside of the bore
after the mandrel is withdrawn.
Hammer-forged barrels are very long wearing due to the com-
pressed surface of the bore. Also, the rifling is usually more
uniform and smoother since it has been formed on the highly
polished mandrel. Hammer forged barrels require no lapping.
Generally, they are quite stable in their vibration patterns
and very accurate. Some hammer-forged barrels require no
straightening and are the most accurate available today.
Button Rifling
Around 1950, Remington was using a type of rifling called
button rifling. To accomplish button rifling, a gunsmith would
pull, some would push, a preformed hardened tungsten-
carbide swedge through the barrel. With this method, the
rifle would end up with a uniform rifling shape, uniformity in
bore and groove finish, and dimensional uniformity. Button
rifling only took about two to five seconds to complete.
Micro-Groove Rifling
In 1953, Thomas R. Robinson invented a rifling method
called Micro-Groove rifling, used by Marlin (Figure 16). This
method of rifling revolutionized accuracy, giving way to high
bullet velocity and low chamber pressure. The Micro-Groove
design has more rifling lands than the conventional barrels,
which results in engraving on the bullet, giving a secure
spinning grip for stabilization (Figure 17).
The grooves of the Micro-Groove barrel are relatively shallow
and the barrel has a bore that’s greater than standard size.
The shallow grooves and larger-size bore result in a less
grooved and distorted bullet or bullet jacket than conventional
barrels (Figure 18).
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FIGURE 16—Micro-Groove Rifling (Courtesy of
Stackpole Books and Marlin Firearms Company)
FIGURE 17—Notice the increased number of landsand grooves. (Courtesy of Stackpole Books and
Marlin Firearms Company)
Rifles 33
Polygonal Rifling
Hechler & Koch (HK) uses a type of rifling called polygonal
rifling (pol i gon al rifling). HK has perfected the polygonal
profile barrel for increased velocity and longer barrel life.
You’ll find the bore of the polygonal barrel to have a rounded,
square, or hexagonal profile (Figure 19). There’s better guid-
ance of the projectile in the bore, which optimizes obturation.
Engraving of the bullet in this type of rifle is considerably
reduced, which increases its service life. Unlike conventional
barrels, the polygon bore traps gas behind the bullet for
increased velocity (Figure 20).
FIGURE 18—The top photo illustrates a conventionally rifled barrel. The bottom depicts a Micro-Groove-rifled barrel.(Courtesy of Stackpole Books and Marlin Firearms Company)
FIGURE 19—The PolygonalRifled Barrel (Reprinted with
permission from HK, Inc.)
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Lapping
Lapping is an operation performed to renew the surface of
both the lands and grooves and to polish the inside of both
smoothbore and rifled barrels. To lap a barrel, it’s necessary
to first make a lap. A lap is a lead plug that’s poured inside
the barrel so it fits perfectly in the grooves and lands. A cork
with a small hole in its center is pushed down the bore to a
distance about four to six inches below the muzzle.
Caution: Never make a lap shorter than four inches as it will
tend to wear out too fast and not follow the rifling perfectly. I
have read some writers who recommend a lap as short as
one inch. This just tells me they have little experience lap-
ping barrels; otherwise, they would realize the short lap
wears too fast and won’t properly follow the rifling. The long
lap prevents the lap from coming out the breech end of the
barrel. It also prevents skipping index when lapping a barrel
in the closed action.
Next, a cleaning patch saturated with high-temperature
grease is run down to the cork and pulled back out so as to
leave a light coating of grease in the bore. The cork should be
pushed about an inch further down the bore with the greasy
34
FIGURE 20—In the conventionalbarrel (A), the bullet (B) is hid-den in a cloud of escaping gas(C). The Polygonal barrel (D)allows the bullet (E) to trapgas behind it, increasing thebullet velocity. (Reprinted with
permission from HK, Inc.)
Rifles 35
patch and then tapped about the same distance back toward
the muzzle after greasing to avoid leaving an ungreased spot
just ahead of the cork.
Caution: Any ungreased spot in the area where you pour the
lap may result in the lap soldering itself to the bore. If this
happens, you’ll experience great difficulty in breaking the lap
loose from the bore.
An 1/8 inch rod at least six inches longer than the barrel is
fixed into the hole in the cork. I use a long one-piece cleaning
rod with a swiveling handle, which allows the rod to rotate
freely to follow the twist of the rifling. Just above the end of
the rod are several small grooves cut into it with a file. The
end of the rod protruding from the barrel is held central to
the bore and melted lead is poured down the bore until it’s
just below the muzzle.
After the lead cools, it’s tapped with a cleaning rod to break
it loose from the barrel. This shouldn’t be difficult due to the
coating of grease placed in the barrel.
If a lap does become soldered in the bore for some reason,
you can remove it by first heating the end of a rod red-hot
with a torch. Then run the hot rod into the lead and melt it
a bit at a time until it comes loose.
Caution: Never heat the barrel enough to melt the lead. Doing
so might ruin the barrel’s heat treatment.
Warning: When working with hot lead, wear appropriate safety
clothing.
The lap is next pulled out of the barrel on the rod, which was
cast into it. The lap is firmly affixed to the rod because lead
fills the grooves that were earlier filed into it.
Before removing the lap from the barrel, make a mark on the
lap that will align with a tiny mark placed in front of one of
the rifling grooves at the muzzle. This will enable you to
replace the lap precisely into the grooves where it was cast.
When the lap has been removed, it should be oiled with light
machine oil and a patch saturated with light machine oil run
through the bore. Then reinsert the lap in the bore, paying
careful attention to the index mark. Be sure to get the lap
seated back in the grooves it was poured in as there are
small differences both in size and profile in different grooves.
With the lap back inside the oiled barrel, it should be pulled
back and forth until it works smoothly the full length of the
bore. Once traveling freely in the bore, it should be removed
and coated with a fine abrasive. In times past, the abrasive
used was volcanic ash dust known as pumice. Today we use
lapping compounds such as the barrel lapping compound
sold by Brownells or the finest grade of valve grinding com-
pound used on automobile engine valves.
After coating the lap with the abrasive, place it back in
the barrel with the marked groove aligned as previously
explained. Then, work the rod that holds the lap back and
forth through the barrel with long, even strokes. Continue
this process until the abrasive has completely polished the
bore. The process requires removing the lap every 75 strokes
or so and running a cleaning patch through the bore to
remove accumulated dirt and lapping residue from the
barrel and lap.
Also, visually inspect the bore to note progress. If the barrel
has been removed from the action or the breech plug removed
from the bore of a muzzle-loading gun, simply look through
the bore at a light source to inspect it.
Note: You should always remove the breech plug from any
barrel being lapped.
Sometimes it’s expedient to lap a barrel without removing it
from the action. In the case of a bolt-action that allows bolt
removal, it’s easy to observe progress. However, when you lap
a barrel in an action that doesn’t allow straight-line viewing of
the bore, it becomes necessary to use mirrors or borescopes,
which require more experience. If possible, you should prac-
tice finding flaws in a barrel using a borescope to become
more skilled in assessing the progress of bore lapping.
Caution: Lapping should proceed so that each bore section
receives equal attention. If a section appears darker than the
rest of the bore, don’t concentrate on lapping that section
more than any other. Doing so will slightly enlarge the area of
concentration and allow powder gas to bypass the bullet. The
result will be gas cutting the bullet and impaired accuracy.
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It helps to think of lapping as hand-planing a board. When a
section of the board’s surface is rough, it becomes necessary
to bring the entire board down to the rough surface in order
to clean it up. The same applies to lapping the bore. The goal
is to achieve a highly polished uniform diameter and contour.
Lapping should continue until the bore exhibits a uniform
highly shiny appearance without dark or shadowy appear-
ances in any section (Figure 21).
Note: When checking progress, remember to remove the lap
and thoroughly swab the bore with clean patches to remove
the accumulation of lead, lapping compound, and oil. Then,
inspect the bore to determine if further lapping is necessary.
The lapping process should continue until you’re totally sat-
isfied with the job. Prior to resuming the lapping process,
you should wash the lap in a small can filled with solvent
and thoroughly wipe it, thus removing lapping residue and
accumulated abrasive. Also, coat the lap with light oil and
run through the bore to lubricate it. Then coat the cleaned
lap with the lapping compound.
Caution: At all times, use the index mark on the lap to avoid
placing the lap in the wrong grooves. Incorrectly inserting the
lap will damage it, and you’ll have to make a new one.
When the bore reaches the point where it’s uniformly bright,
it’s time to finish lapping with a finer-grade abrasive. I gener-
ally finish lapping with a very fine abrasive such as J-B
Cleaning Compound or X-Bore barrel cleaner. Either product
FIGURE 21—This photo depictsa barrel in a vise in a lappingposition.
provides a really fine finish to the lapped bore, helping to
prevent metal fouling while increasing accuracy potential.
After you’re satisfied that the bore is properly lapped, thor-
oughly clean and wipe it to remove abrasives and lapping
residues.
Caution: Faulty lapping can as easily ruin a bore as improve
it. You should carefully follow the instructions just given to
restore a worn barrel to top-notch accuracy. Improved accu-
racy will bring repeat customers and new customers willing
to pay well for the restoration of their favorite guns to good
shooting condition.
Lapping is especially useful in barrels that have been allowed
to rust; accuracy is lost as a result of buildup of metal foul-
ing in the rusted areas. Lapping is also useful in restoring
barrels that have lost their best accuracy due to erosion just
ahead of the throat section. It’s not possible to completely
remove the eroded portion of the barrel, but it’s possible to
smooth out the eroded section and regain accuracy.
Lapping Shotgun Bores
While this unit concentrates on rifles, the gunsmith can also
benefit greatly from knowing how to lap shotgun bores. Since
most instructions for lapping rifle bores pertain to shotguns
as well, I have included a few extra paragraphs to impart this
invaluable information.
It’s easier to lap shotgun bores since there are no groves to
fill and the lap plug moves much easier through the bore.
However, in a choked barrel, the lap must be poured in the
section of the bore behind the choke. It won’t work in the
tapered section of the choke. I know one gunsmith who claims
he pours the lap right up to the muzzle and it works fine.
This has not been my experience. You don’t need to use an
index mark on a shotgun lap as it will be rotated in polishing
the bore. However, the lap must be removed from the breech
for cleaning and oiling, as it won’t pass the choke section.
The best method I know for restoring a shotgun barrel is to
pour a lead lap below the choke section and attach it to a
rod with deep grooves cut into it to hold lead. A swiveling
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arrangement isn’t necessary, as the lap should be rotated in
a shotgun bore. The lap can be attached to an electric hand
drill and run back and forth in the bore while the drill
rotates it. This allows for very fast cutting and restores the
barrel quickly.
In the choke section, use a wooden dowel that’s slit with
a hacksaw for a short distance. Wrap a fine-grade emery
cloth—emery side against the bore—around the dowel, and
attach it by inserting the ends in the slot cut in the dowel.
You can oil this emery cloth and spin it with the electric
hand drill to quickly polish the choke section.
You can polish the choke section using cotton bore oil of the
proper gage to which a liberal amount of lapping compound
has been applied. Again, the cotton bore oils are spun with
a hand drill.
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Self-Check 3
Indicate whether the following statements are True or False.
_____ 1. Alluminum barrels with steel liners were unsuccessful because the light weightallowed too much vibration.
_____ 2. SAAMI specifications were set up to furnish a standard to which all American manufactured arms and ammunition could be compared and as a standardizationsystem for the formerly chaotic manufacturing tolerances of the firearms industry.
_____ 3. A shorter barrel is required for overbore cartridges.
_____ 4. A burnishing tool works by compressing and soothing the bore surfaces.
_____ 5. The barrel weight of a rifle isn’t important to it’s accuracy.
Check your answers with those on page 129.
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BARREL STEELS
To teach barrel making is beyond the scope of this course.
However, we’ll discuss properties of various barrel steels that
will help you select the proper barrel blank for your cus-
tomers’ rifles.
Today, barrel manufacturers use four general categories of
steel:
• Black powder, or gun barrel grade, carbon steel
• Ordnance, or high-power carbon, steel
• Nickel steel
• Stainless steel, often known as rustproof steel
The four general categories encompass many different trade
names used by various barrel makers. Each barrel maker
claims certain superior advantages for its barrels and there
are some differences. However, the steel used in making a
barrel, provided it’s the proper strength, isn’t nearly as
important as the methods and quality of workmanship used.
Black Powder, or Gun Barrel Grade,Carbon Steel
Black powder carbon steel is relatively soft, plain carbon
steel. After wrought iron passed from the scene, manufactur-
ers used this steel for building black powder rifles. Its use is
now limited to barrels intended for muzzle-loading rifles and
other loadings that won’t generate over 25,000 pounds per
square inch. Black powder steel doesn’t have the tensile and
shear strength to withstand modern high-power cartridge
loadings, which generate pressures in excess of 25,000
pounds, but it’s acceptable for rimfire .22 caliber barrels.
A few years ago there were serious problems with some steels
used in imported black powder muzzle-loading rifles. The
problem was that foreign black powder barrel makers used
extruded steel to which a significant amount of lead was
added to facilitate the extrusion process. The steel was
extruded as the finished outside of the barrel with a hole
through its center.
The hollow center enabled the barrel to be made with minimal
machine work. First, a reamer was run down the extruded
bore to clean it up abit. Then a rifling broach was pulled
through the bore. This quick-and-easy process made it
possible to produce barrels very inexpensively.
However, the weakening effect of the lead and the arrangement
of the steel’s grain caused by the extrusion die caused prob-
lems. As it turned out, aligning the steel grain lengthwise
along the axis of the barrel resulted in good linear strength,
but unbelievably poor hoop strength. This caused quite a few
barrels to burst or “goose egg” (swell in a barrel section) with
loads that should have been perfectly safe. This situation
continued until some of the more knowledgeable black powder
shooters and writers made enough fuss to get it corrected.
Note: Many sections of burst muzzle-loading barrels are still
scattered around the hills near my test site here at Falling
Waters, WV (Figure 22). This is the result of a series of proof
tests done for a black powder magazine on suspect barrels,
which blew with only moderate proof loads. At the other
extreme, barrels made by several manufacturers withstood
very heavy proof loads without incident. Getz, Green
Mountain, and Thompson Center barrels required heavy
loads of fast-burning smokeless shotgun powder to burst
them during the destructive testing phase.
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FIGURE 22—Shown is a sec-tion of a burst muzzle-loadingrifle barrel. Failure to properlyseat the ball caused theaccident.
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Other reputable manufacturers such as Lyman and Navy
Arms also made good strong barrels through this period.
The gunsmith should have no qualms about using these
companies’ products. After the appearance of a series of
magazine articles concerning the problems engendered by
inferior barrels, the situation rapidly cleared up. To the best
of my knowledge, all rifle and most other barrels being sold
presently in the United States and throughout North America
are of a good-grade homogeneous steel.
Ordnance Steel
Ordnance steel, or high-power carbon steel, is the type used
in most gun barrels intended for use with today’s high-power
cartridges. While the composition of ordnance steel varies
among manufacturers, it usually contains additives in the
following amounts.
Manganese 1.00%–1.30%
Carbon 0.45%–0.55%
Phosphorus (maximum) .05%
Sulfur (maximum) .05%
The majority of high-power rifle barrels made in recent
decades are composed of ordnance steel. A few of the larger
manufacturers who used ordnance steel in their barrels are
Remington, Savage, G.R. Douglas Barrels, and Springfield
Armory.
Names for ordnance steel have changed in the last few years,
with many firms claiming to have different new steels.
Frankly, I don’t find much difference as far as machining
properties and other characteristics are concerned. As this is
a carbon steel, it’s usually heat-treated. Variations in work-
ing properties as well as tensile and shear strength are con-
trolled by the heat treatment. Therefore, you must avoid
overheating this steel unless you intend to heat treat it after
your work. Also, heat treatment is a process that requires
high-temperature furnaces and solid knowledge of a subject
that’s beyond our scope.
Nickel Steel
The Winchester Repeating Arms Co. and some other barrel
manufacturers use nickel steel. Rock Island Arsenal, Niedner
Rifle Corporation, and most British rifle makers are among
the larger users of nickel steel.
Nickel steel is also popular with custom barrel makers, as
many shooters desire its ability to withstand bore erosion as
well as its improved corrosion resistance. Nickel steel is a
very fine barrel steel with many highly desirable qualities.
While it’s not a “stainless” steel, it does have superior protec-
tion against rust, due to its three percent nickel content.
High-power carbon steel seems to wear faster than nickel
steel and is very susceptible to rust. Nickel steel runs
.030–.040 carbon. It’s an acid open-hearth process steel.
Many think open-hearth steels, due in part to oxygen expo-
sure at high temperature, have more resistance to corrosion.
Nickel steel is more difficult to blue than ordnance steels, and
when it is, the bluing seems to wear off faster from handling
than other type steels. Many of us can remember Winchester
Model 12 shotguns and Model 70 rifles belonging to our
fathers and grandfathers. Their almost silvery color was the
result of the bluing wearing off after many hours in the field.
Stainless Steel
Stainless steel is also known as Rostfri, Rust-Proof, Anticoro,
and Antinit steel. Apparently, these “stainless” steels are the
wave of the future, at least in the better grade of higher-
priced barrels. Much of this steel is imported from Austria,
Germany, and Sweden. Technically, they’re not actually
steels; instead, they’re high-chrome iron. The exact formulas
and manufacturing processes are proprietary secrets, closely
guarded. Recently, there have been some American-made
stainless steels used in gun barrels, and these seem destined
to fill a larger portion of the gun barrel market. Again, the
exact composition and manufacturing processes are propri-
etary, but their compositions are basically about 14 percent
chromium, 0.10 percent carbon, and 1.50 percent copper.
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Stainless steels are very difficult to machine and wear even
carbide cutters very rapidly. Chromium steel is abrasive due
to its hardness factor. I’ve heard that the copper is added to
increase machinability, and I know that these steels are put
through very complex heat-treating processes to attain the
level of machinability they do have.
Even stainless steels aren’t actually rustproof, which I learned
the hard way by making a muzzle-loading barrel from Inconel
stainless. I hoped to eliminate the messy process of washing
out the bore with soap and water, wiping it dry, and oiling it
after a thorough drying. If you have a muzzleloader, you’ll
understand what one goes through to clean it after a day of
shooting. My new stainless steel barrel, which I so painstak-
ingly made and polished, rusted over a period of time from
the acid and other residues of black powder. It rusted much
more slowly, but it did rust.
To the best of my knowledge, a truly rustproof steel does
exist for black powder use. This is a fairly soft metal, not
exactly steel, known as “Monel.” Monel isn’t strong enough for
any barrel use except black powder. Even so, it’s only mar-
ginally strong enough for even the lightest loadings in wall
thickness that shooters can conveniently carry. Furthermore,
Monel is so difficult to machine that I wouldn’t make another
barrel from it for 10 times the price!
Monel’s lack of yield strength requires a heavy-walled barrel,
which is too cumbersome to carry comfortably in larger cal-
ibers. As a result of a test I performed, I say it lacks yield
strength. I tested a section of Monel tubing with a .375 bore
and .750 outside diameter, which would be considered heavy
enough for a muzzle-loading barrel of ordinary steel. When
fired with patched .370 ball in front of 90 grains of FFFg
black powder, it swelled up in a goose egg! While it didn’t split
or burst, it would have ruined any stock if inletted. Actually,
the load wasn’t even a proof load. At a light proof load of four
grains per caliber, 150 grains would be considered a proof.
The tube failed at 60 grains below proof! Furthermore, this
“smoothbore” had not been subjected to the weakening
effects of rifling grooves.
Had the Monel tube withstood proof loading and further
testing with double-charge, double-ball proof loads, it would
have been rifled and further pursued. As it failed initially,
there was no reason to continue the experiment further.
Stainless barrels are difficult to machine, complex to heat-
treat, expensive, and difficult to blue or brown. Therefore, I
don’t recommend becoming involved with them except when
purchasing and installing finished, ready-chambered, barrel
blanks. Even then, I recommend involvement only if you have
a lathe set up to handle precise shouldering in tough, hard
steels. Adding or removing a turn of threads to maintain
headspace with stainless steel barrels is a different class of
work than the same operation on an ordnance steel barrel.
Even if your shop is equipped for rebarreling with stainless
steel, the difficulty of bluing or browning it remains. The
method most commonly used for bluing is to electroplate the
stainless barrel with black nickel. Stainless barrels can also
be electroplated with soft iron and blued using hot salt bluing
processes; or they can be copperplated, and the copperplating
chemically blackened to form an acceptable appearance.
Modern shooters are beginning to accept bright polished
stainless steel barrels, but they’re not suitable for hunting.
The bright shine and flashes of light from the barrel alert
game to the hunter’s presence.
The purpose of discussing stainless steel isn’t to discourage
the gunsmith who’s equipped for stainless steel barrel work
from trying it. By all means, try it on one of your own actions
in a chambering you can personally use. Then, consider fur-
ther work. My intent is to forewarn you about possible diffi-
culties of which you should be aware.
Installing a Barrel on an Action
Often a customer will bring in a rifle with a barrel that for one
reason or another has been ruined. The most common cause of
a bad barrel is failure to clean it after shooting. Most shoot-
ers start out their shooting experiences with .22 rimfire rifles.
The .22 rim fires, with the exception of the .22 Winchester
Magnum, use greased lead bullets. The greased bullets leave
a coating of grease on the bore that acts as a rust inhibitor.
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So, it’s not necessary to clean such guns after every day of
shooting to prevent rust. Most shooters just clean them occa-
sionally to remove accumulated lead and grease. This works
well enough for an inexpensive .22 plinker, but you should
always clean a gun after shooting it.
In any event, problems arise from shooters who assume they
can get by without cleaning their high-power rifles after every
shooting session. This just won’t work with high-power rifles
that don’t use greased bullets. The intense heat and pressure
inside the barrel vaporize any cleaning oil remaining from the
previous gun cleaning. The bare, dry bore quickly rusts from
residual atmospheric moisture. Within a few months of not
being cleaned after firing, especially under such high-humidity
conditions as are found in the Southern and Eastern United
States, the barrel rusts beyond restoration, even by lapping.
The easiest way to get the customer’s gun working again is
to order a new barrel from the manufacturer, remove the old
barrel, and install the factory replacement. This eliminates
a lot of problems, as the barrel will have the right threads and
the contour will fit the stock. All you have to do is remove
the old barrel and replace it with the new barrel. This proce-
dure requires certain skills. First, you must fit the barrel
properly to the action. Then it must be correctly headspaced.
We cover chambering and headspacing in the next study
unit. Following is an inexpensive method for removing and
installing a barrel on an action.
Removing the Old Barrel
You can remove a threaded barrel from an action easily with
simple tools. Assuming that you already have a heavy bench
vise, you’ll need
• Two small blocks of hardwood
• A pick handle (or baseball bat)
• A 15 foot piece of 1/2 inch nylon rope (silk rope is even
better)
• Some rosin—the type used on violin bows is fine
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First, cut two hardwood blocks to the rough shape of the
action. Place the barreled action between these blocks and
tighten them in the vise.
Note: In this example, the muzzle should
extend out to the left of the vise (Figure 23).
Then, liberally sprinkle rosin on the rope,
fold it in two, and hold its open ends against
the barrel with your right hand.
Note: You should replace the open ends
about midway down the barrel pointing
toward the breech. The looped end should
extend past the muzzle.
Next, with your left hand, wind the looped
end of the rope around both the barrel and
the rope already resting against it. Begin at
the muzzle and lap the rope over the barrel, pulling it back
toward you from under the barrel.
Note: Getting the overlap started takes a bit of practice, but
you’ll quickly get the hang of it. Especially when beginning
the lap, hold tension on the rope to prevent it from coming
loose. Wind up all of the rope but the remaining loop, and
be sure to leave the open loop big enough to insert the pick
handle.
Place the pick handle in the loop and begin to tighten it.
You’ll be pushing the handle over the barrel and then pulling
it towards you. The object is to tighten the rope against the
barrel, thus creating counterclockwise force.
Note: With your left hand, hold the rope tightly at the muzzle
end to prevent slack.
Once the rope is sufficiently tight, the rosin will grab the
barrel and the wooden handle will act as a lever to rotate
the barrel out of the action’s right-hand threads.
Installing the New Barrel
A new factory barrel should screw into the action fairly easi-
ly, up until the last quarter turn or so when it should begin
to tighten up. Wind the rope around the barrel in the other
direction to tighten it into the action. Turn the barrel tight
48
FIGURE 23—Illustrated Barrel Removal Procedure
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until the index marks on the action and barrel line up. In
some instances, you’ll have to insert a thin shim in front of
the barrel shoulder if it turns past the index mark before
tightening up. Conversely, some barrels will tighten up
too soon. You might have to take a tiny slice off the barrel
shoulder—not more than .005 inch at most. Align the index
marks to ensure that the sight slots are square and that the
barrel properly aligns with the action.
Caution: Never face any metal off the front of an action to
allow barrel index mark alignment. I’ve seen evidence of this
work performed by so-called gunsmiths whose interest lies
more in making money than doing good work. Facing metal
off the front of the action permanently alters its alignment,
and any future rebarreling of the action will be very difficult.
Selecting Barrels
When you set out to select the proper weight and contour for
a barrel to install on a customer’s rifle, many considerations
come into play (Figure 24). First, there are customer desires.
Does the customer want a lightweight rifle, a field weight
hunting rifle, a varmint weight barrel, or perhaps even a
bull barrel?
After determining the customer’s wishes, you must consider
the balance of the rifle. The balance point, except in a bull
barrel, should be just in front of the trigger guard. It can
vary a couple of inches from this point, but anything over
FIGURE 24—This drawing depicts barrel contours.
this is going to feel either muzzle light, or muzzle heavy.
Therefore, you must consider the weight of the action and
the caliber of the bore. Given the same outside contour and
length, a .22 caliber barrel is going to be somewhat heavier
than a .30 caliber barrel, and a lot heavier than a .44 caliber
barrel the same size. Except for target shooters and varmint
hunters, no one wants to add weight to a rifle. Considering
that the barrel weight counterbalances with the weight of the
action and buttstock, keeping the balance point in the right
place severely limits the options for barrel contour. Many
beginning gunsmiths forget these factors and end up with
ungainly, clumsy-handling, out-of-balance rifles on their first
try at rebarreling.
Using the Springfield 1903A3 action as an example, a .30
caliber barrel will have a straight section 1.140 inch diameter
from the shoulder to a point 1.250 inches ahead of the
shoulder. Then it will go into a straight taper from the 1.140
inch diameter front end of the straight section to a diameter
of .955 inch over the next 1.750 inches. From the .955 inch
diameter, it will have a straight taper to around .648 inch at
the muzzle to fit standard sight bands. Obviously, the taper
will be faster and the barrel lighter if it’s cut off at 22 inches
than it would be if it were left 26 inches long.
Back in the days when we could obtain a good Springfield
1903A3 for $15.50 plus $3.00 shipping, a grand total of
$18.50 for this splendid rifle, gunsmiths were busy “sporter-
izing” Springfields. Sporterizing generally consisted of cutting
the barrel off to 22 or 24 inches, turning the barrel lightly to
smooth it up. Then you replaced the stock with a “sporter”
style stock from Reinhart Fajen, Bishop, or Herters, who
supplied nice stocks pre-inletted for Springfield actions and
standard contour barrels as dimensioned above. Usually, the
gun was reblued, and drilled and tapped for scope mounts.
After the metalwork had been completed, a hole was drilled
into the buttstock under the buttplate. This was done to
lighten the butt section if the balance point was too far to the
rear, or a bit of lead was inserted in the forend to move the
balance point forward. Suppose the customer insisted on
keeping a muzzle-heavy rifle as light as possible. Then, a
faster taper would be turned on the barrel from the end of the
taper in front of the straight receiver section to the muzzle.
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Otherwise, a piece of lead would be inserted in a hole under
the buttplate.
The heaviest rifle barrels intended for “offhand” shooting,
given a 1.250 inch diameter over the chamber, would carry a
straight taper from the front end of the cylindrical 1.75 inch
length at the chamber, to around .880 inch at the muzzle.
This taper provided about as heavy a barrel as a shooter
could hold up offhand and maintain accuracy.
Most hunting rifle barrels have a muzzle diameter of .647
inch to allow for front sight bands such as those used on
the ‘03A3 Springfield. Even if you don’t plan to use a barrel-
band type sight, it’s good to consider using a standard muzzle
diameter so you can fit the sight of your choice. Often front
sights are “sweat” soldered onto the muzzle. Such installations
allow for a bit of circle diameter tolerance. Still, to properly
install the sight, consider which barrel diameter sights are
available before finishing the muzzle diameter to a size that
requires boring a sight base radius. You can avoid this time-
consuming job by using a standard sight base radius as the
final muzzle diameter.
As previously mentioned, 22 to 24 inches is the standard
length barrel for high-power rifles in the medium calibers,
although most gun makers like to use 26 inches for the
heavy calibers such as the .300 magnums and .375s. Muzzle
flash and blast become more unpleasant as barrel length
decreases, and even though velocity loss is slight with short-
er barrels in these calibers, they’re unpleasant to shoot. If a
customer insists on a .375 magnum carbine with an 18 inch
barrel, make sure he or she understands that shooting it
won’t be an enjoyable experience. Place in writing that you,
as a gunsmith, advise the customer of the problems encoun-
tered by such a short barrel. Then, if you end up with an
unhappy customer, you won’t be stuck with an unwanted
gun.
Of course, you must consider power as well as the bore
diameter when determining the minimum diameter and
length of a barrel. Low-powered rounds, such as the .25-20,
may be of much smaller diameter and length without either
excessive muzzle flash and blast, or severe impairment of
accuracy. Using good ordnance steel, a .22 rimfire barrel may
be made as small as .580 inch at the breech and .375 inch
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at the muzzle without danger of being damaged from the
pressure of the loading. Such a barrel wouldn’t be as accu-
rate as a stiffer, heavier barrel due to barrel vibration.
Turning Down Barrels
Customers will often ask the gunsmith to turn down barrels
to make them lighter. If you have sufficient metalworking
experience and a lathe, this could earn you some money.
However, you must prepare for the turning to release stresses,
which will cause the barrel to bend regardless of how careful
you are. When this first happened to yours truly, I assumed
that I had somehow inadvertently bent the barrel.
It was a Springfield barrel I had mounted with a driving dog
on the action flat and a plug the size of the bolt with a center
in it fitted on the face plate and center of the engine lathe.
It was wobbling in the lathe, and I was afraid I was going to
have to replace the barrel. In an effort to straighten the bar-
rel, I placed a steel bar under the tracer attachment bar.
I then used it as a lever to bend the barrel back straight so
I could finish turning the barrel. Using a dial indicator, I was
able to true the barrel within two thousandths of an inch and
continue turning until it again warped and started wobbling
against the cutting tool.
I eventually learned to go ahead and finish turning barrels
(unless they went so far out as to make an interrupted cut)
and then straighten them when I had finished. If they go too
far out, I have learned to tap them reasonably straight with a
lead mallet and then straighten them properly after turning.
Barrel Straightening
This brings us to barrel straightening, a very difficult process
requiring great expertise, regardless of what some would
have us believe. I don’t recommend the process unless you
gain hands-on experience working under qualified supervi-
sion. However, I overview the task briefly in the interest of
further knowledge. In brief, I accomplish barrel straightening
by placing the barrel across two heavy steel fingers and
applying pressure to it between the support points so as to
bend it the necessary amount.
52
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To judge straightness, I point the barrel toward a window
with a dark bar across it. I straighten the barrel by looking
through the barrel at the shadow of the bar in the window,
and by bending the barrel until there are no offsets or curves
in the shadow of the bar in the barrel.
Recoil Compensators
Recoil compensators reduce recoil by directing the energy
of the gases in the barrel against a shoulder or series of
holes at the muzzle. The gases drive forward on the barrel
in opposition to the recoil. There are two basic types of recoil
compensators, with many variations of the basic types.
One type is a series of holes or slots milled into the barrel at
the muzzle. The other type is an attachment that’s screwed
or sweated (soldered) onto the muzzle (Figure 25).
Each type of recoil compensator has advantages and disad-
vantages. The screw-on type is difficult to install unless you
have a lathe to turn down or thread a short section of the
muzzle on which the compensator is installed. Whether
threaded or sweated in place, the compensator must be
exactly true with the axis of the bore if the rifle is to shoot
accurately. Any misalignment will cause different gas pres-
sures to bear on the bullet and deflect it from its true course.
FIGURE 25—A Shal-Cut Muzzle Brake Mounted on a .300 Weatherby Rifle
If you’re installing a threaded recoil compen-
sator, first determine the thread size and
pitch. Then, if at all possible, cut the threads
onto the proper length of threaded area at
the muzzle. If the barrel is centered in a
lathe that has a live (revolving) center, set
a centering plug into the muzzle. You can
easily make a centering plug by turning the
shank of a properly sized bolt (3/8 inch will
do for most rifles of .25–.35 caliber) to a
point where it will just fit nicely in the bore
of the barrel (Figure 26).
Cut a relief groove at the base of the head to ensure that the
bolt head seats squarely on the muzzle of the gun. Center the
head of the bolt using a 60° center drill and insert the plug
into the bore at the muzzle to support it during machining.
Then, cut the threads onto the barrel. The compensator will
be true to the bore, and no problems will arise.
It’s a timesaving idea to cut the threads down to within a few
thousandths of an inch of the finish pitch diameter of the
threads and then run a die down over the threads to finish-
size them. This is much less time-consuming than cutting
the threads to finish size.
After cutting the rough threads, remove the barrel from the
lathe and carefully start the die onto the cutting threads to
finish-size them.
Note: If your lathe isn’t set up to cut threads, you can center
the barrel in the head stock and remove the center from the
tail stock. Turn the thread’s maximum diameter on a short
section of the muzzle. Then use the face of the tail stock as a
guide to hold a die square with the barrel and run the die the
desired distance down the barrel. Be careful! This method
might result in threads that aren’t entirely square with the
barrel and might cause accuracy problems.
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FIGURE 26—This drawing depicts a lathe centerplug for a muzzle.
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You make the second type of recoil reducer by cutting slots
or holes into the barrel near the muzzle. The holes are angled
to the rear about 10° to direct the gas to the rear and coun-
teract recoil. The problem with cutting such slots and holes
is that any burrs or rough edges that remain inside the bore
will severely impair accuracy.
When you use a barrel-porting recoil reducer, you cut the
holes in the barrel with an electronic discharge machine (arc
borer), which works on the same principle as an arc welder.
The electronic discharge machine erodes metal under arc
and makes a perfect cut, leaving no burrs. The actual cutting
tool is a carbon rod that carries an electrical charge from an
arc welder and “eats” the metal away by electric sparks as
you move it into the barrel. This method doesn’t cause any
burrs or roughening of the bore. The barrel porting system
doesn’t add length, diameter, or weight to the barrel. The
most popular process for barrel porting is patented by
Magnaport International.
Note: I recommend that you send customer rifles to
Magnaport to have the barrel-porting recoil reducer work done
and charge a fair markup. Magnaport has the specialized
jigs, fixtures, and tools to do the job correctly. These tools are
far too expensive for the individual gunsmith to buy due to
the relatively few jobs that will come your way. It’s important
to realize that a professional often gets paid for his or her
knowledge as well as actual work. In this instance, knowing
where to get the job done correctly is worthy of profit.
Flash Suppressors
Flash suppressors are metal tubes attached to the muzzles of
guns to keep the muzzle flash from being visible to the
enemy during combat or similar situations. They can hide
the flash from all directions except the position in front of the
bore. Flash suppressors can be made from a section of thin-
wall tubing that’s soldered or threaded onto the muzzle using
an adapter to fit the muzzle (Figure 27). They work on the
principle of having a large enough shielded chamber to con-
tain the muzzle flash. There’s not much interest in them
except by those who are into military collecting and want to
have an authentic-looking weapon.
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FIGURE 27—Flash suppressors are available in several styles. (Drawing courtesy
of David Capobianco Co.)
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Self-Check 4
Indicate whether the following statements are True or False.
_____ 1. Recoil compensators work by directing some of the gas against a series of holes or slots in the compensator to allow the force of the gas to push the barrel awayfrom the shoulder.
_____ 2. Using stainless steel in a gun barrel eliminates the need to clean the gun as it willnever rust.
_____ 3. Extrusion is a good method to use in making barrel steel.
_____ 4. In turning a barrel, the muzzle should be centered on a live center running on a pluginserted in the muzzle.
_____ 5. Barrel straightening is accomplished by running the barrel under a dial indicator andbending until the indicator reads true along the full length of the barrel.
Check your answers with those on page 129.
TRIGGER MECHANISMS
Triggers and sears can be the most sensitive and dangerous
parts of a rifle. Accordingly, trigger work is an advanced skill
best left to those with specialized hands-on training and
extensive experience. Due to the danger of accidental discharge
resulting from a malfunctioning trigger and the potential for
liability, a growing number of manufacturers refuse to sell
replacement parts for triggers to anyone, including professional
gunsmiths. Manufacturers don’t want gunsmiths to perform
trigger work. Instead, they urge gunsmiths to send guns
requiring trigger work back to the factory for service. Some
manufacturers even conduct armorer schools where students
train specifically to repair the manufacturer’s firearms
(including trigger mechanisms). A student who successfully
completes such training can then obtain a license to do work
by the manufacturer.
Warning: You must weigh the dangers associated with doing
trigger work, the potential for liability, and the high cost of
insurance—much higher than for other gunsmithing tasks—
before you take in this type of work. Furthermore, unless you
have access to hands-on instruction from a professional, you
must gain sufficient experience by training yourself on your
own firearms. Considering these factors, I strongly advise you
to turn down all trigger work.
Anyone who has tried the trigger pulls on rifles made in the
last few years is well aware that rifle manufacturers are also
running scared for fear of accidental discharge and resultant
legal complications. The trigger pulls of new rifles have gone
from comfortable 25–40 ounce pulls to stiff, difficult-to-shoot
100–150 ounce pulls. The latter are almost impossible to
shoot accurately from an offhand position, and competent
shooters are almost sure to bring their new rifles in to have
such atrocious pulls corrected. You must develop your own
policy for such situations and stick to it.
Also, there are situations where a trigger mechanism breaks
or becomes worn to an unsafe condition. All too often, a
“basement gunsmith” renders a trigger mechanism unsafe
due to either ignorance or foolishness, and sometimes trigger
mechanisms become inoperative as a result of faulty or broken
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parts. Such situations are difficult for the gunsmith. One
cannot realistically expect to discard an entire rifle because
of a broken or maladjusted trigger, and the customer may
argue his/her case well.
In another situation, a good customer may insist on your
making the 10 pound trigger on a newly purchased rifle into
a shootable 2 pound pull. Since your customer bought the
rifle from you, he or she may insist that you adjust the pull
or lose a customer. The customer may feel that it’s your duty
to make the rifle shootable. In a situation where no mechani-
cal problem exists and the customer “pleads” for your help,
you might begin to weaken.
If a good customer “twists your arm” and convinces you to
do work on a trigger mechanism, at least follow these simple
rules.
• Don’t do any trigger work until you’ve had sufficient
hands-on training and know what you’re doing.
• Never drop a pull below minimum factory specifications.
• Don’t perform any work that will compromise a firearm’s
safety.
• By all means, carry liability insurance.
• When possible, improve trigger pull by installing after-
market assembly designed to produce the type of pull
the customer wants.
Trigger Adjustment
Many rifles have adjustable triggers that allow adjustment of
the depth of sear engagement and the spring tension.
Rifle triggers that have no adjustment are usually the simple
sear-and-hammer type, such as the notch sear of the
Winchester Model 94, and many other rifles having hammers
with cut sear and safety notches. The trigger used in the
Winchester M 67, Springfield 03–A3, and a myriad other
rifles have slightly different sears that operate on the same
principle. Such a trigger, regardless of what action it’s on,
can be improved by carefully stoning the sear to smooth it
(Figure 28). When stoning a sear, make it to engage
across the full area of the notch or bar to reduce
friction and wear. Reduce friction by distributing
the load over a wider area with less pressure at any
given point.
If there’s slightly excessive engagement that causes
creep, carefully stone the sear to reduce engage-
ment to a safe point.
Note: Creep is movement of the trigger before it “breaks,”
which is the term for the point at which a trigger releases the
sear and fires the rifle.
If there’s a deep overengagement, the best policy is to drill a1/16 inch hole in the hammer or sear bar at the point where
the sear engages. Then, insert a short section of a 1/16 inch
diameter nail into the hole (Figure 29). The sear will strike
this nail, which will eliminate overengagement. Then file the
nail until you attain proper engagement.
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FIGURE 28—Pictured is a Hard ArkansasSlip Stone for stoning sears and triggernotches.
FIGURE 29—Rotating hammerand simple sear type triggerassembly showing how toinsert a pin to control thedepth of sear engagement.(Drawing courtesy of David
Capobianco Co.)
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You must not change the angle of the sear or sear notch
unless you have to decrease the angle to eliminate the sear
having to cam the hammer or striker back to disengage. If
you must remove this much metal, you should use a fine cut
Swiss Grobet needle file. Be careful not to remove too much
metal or to decrease the angle too much.
Normally, such sear work is done by honing, which requires
a fine grade of hard Arkansas stone with a knife-edge made
especially for such operations as stoning trigger notches and
sears. Hold the sear or notch in a secure position where you
can set the stone at the proper angle and gently hone the
required surface. Often a simple stoning and polishing,
which smoothes up the engaging surfaces, will suffice to
lighten a heavy pull or take the drag out of a rough one.
Another problem often encountered while trying to develop
good trigger pull is that the sear is too soft to slide easily
against the hammer. This can be remedied by case-hardening
the sear.
When removing substantial amounts of metal from sears, it’s
common to remove the steel’s case-hardened surface. This
situation also calls for rehardening.
Warning: If a trigger’s sear engagement fits into the hammer’s
half-cock notch on the end of the trigger, don’t file the sear
so short that it doesn’t bottom out in the half-cock notch.
Suppose the sear end of the trigger wedges into the half-cock
notch of a rifle with a solid tool steel hammer. The half-cock
notch might break off from metal contraction if you set the
gun in the half-cock position in warm conditions and then
take it into near-zero temperatures. This is very dangerous,
as an accidental discharge can occur. The sear must bottom
out in the half-cock notch as shown in Figure 29.
Removing Two-stage Triggers
Other trigger work concerns removal of two-stage triggers from
military rifles such as the Springfield and the ‘98 Mauser.
You can use many methods to accomplish this worthwhile
end. I prefer to drill the sear bar and tap the hole for a #6–48
screw. I then adjust the screw to the desired sear engagement
and lock it with a #6–48 locknut. This will gave you a nice,
easily adjusted trigger. You can also use a short piece of a
nail or pin, but you can’t easily adjust the nail (or pin).
Whenever possible—as when working on military rifles that
have a sear bar and room for an adjustment screw—use an
adjustment screw.
Aftermarket Triggers
Aftermarket triggers are available for many of the more
popular rifles. Timney and Canjar are just two aftermarket
trigger manufacturers whose products have given me com-
plete satisfaction. Several other makes are available, and I
have heard good reports on most of them. Available in many
different types and models, aftermarket triggers are particu-
larly useful for replacing Enfield, Springfield, and Mauser
triggers when these military rifles are converted to sporting
rifles. Installation is simple. Just faithfully follow the instruc-
tions that come with the triggers. Some aftermarket triggers
fit several different models and the rifle and/or trigger often
requires grinding and filing to obtain proper fit.
Aftermarket models available include single triggers that
work just like the original triggers, simply pulled to fire the
rifle. Their advantage is that they’re adjustable to whatever
weight pull the shooter desires and have a clean, crisp break
without creep or overtravel.
Note: As mentioned, creep is movement of the trigger before
it “breaks,” which is the term for the point at which a trigger
releases the sear and fires the rifle. Overtravel is rearward
movement of the trigger after it breaks. Overtravel can be a
problem as the sudden release of tension on the trigger finger
can cause the gun to lift in the shooter’s hands and shoot
high. A good trigger shouldn’t give much evidence of moving
before it breaks and shouldn’t have any noticeable movement
after breaking. This helps the shooter maintain a proper hold
as he or she fires the rifle.
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Set Triggers
Set triggers are also helpful in maintaining a steady hold
when firing. Two basic types of set triggers are available, with
variations on each type. The most common type is the double
set trigger, which is actually two triggers, one behind the other.
Usually the front trigger is the “set” trigger; the rear trigger
is the “setting” trigger. When you fire a double set trigger,
the setting trigger is pulled first until it clicks to indicate that
the set trigger is ready to be fired. When the setting trigger is
pulled, a weight (sometimes called a fly bar) is pulled down
against a spring, and latched onto the front of the set trigger.
The set trigger has a very light setting, often only a few
ounces. When pulled, it releases the fly bar, which springs
up and knocks the sear out of the notch, thus firing the gun.
There are various mechanical differences in the double set
trigger, but the general principles involved are the same.
The second type of set trigger is the single set trigger. This
type has only one trigger. The trigger is first pushed forward
until it clicks to set it. Then it’s pulled in the normal manner
to fire the gun. This type is rather touchy and hard to adjust.
Once either type of set trigger has been set, it will work with
equal ease to fire the gun.
Note: Both types of set triggers will fire the gun from an unset
position; however, the trigger pull will usually be very heavy
from the unset position.
As stressed early on in this section, if you choose to perform
trigger work, you should exercise the utmost care in installing
and adjusting triggers. You shouldn’t set the trigger, for
example, below a 12 ounce pull until the shooter has become
very familiar with its operation. Discourage the shooter from
regulating the weight of pull.
Finally, before performing trigger work or any other work on
a firearm, you should have the factory manual for it in front
of you as a reference/ study guide. If the exact manual isn’t
available, carefully study the manual for a similar gun. Never
rush blindly into tearing a gun apart.
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Self-Check 5
Fill in the blanks in the following statements.
1. _______ is the movement of the trigger before it “breaks.”
2. A simple hammer-and-trigger type sear should bottom out in the _______ notch.
3. Prior to performing any trigger work, you should have sufficient hands-on training as wellas _______ insurance.
4. The _______ trigger mechanism is a good answer to the gun that doesn’t have a goodadjustable trigger.
5. A trigger or sear that’s too soft is dangerous and should be _______.
Check your answers with those on page 130.
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FIREARM FUNCTIONS
The heart of any firearm is the action, which consists of the
arm’s moving parts and housing. We usually call the housing
the receiver, into which the barrel is threaded or otherwise
locked. In all guns, except the blowback-type action, the
action accomplishes eight functions.
Feeding. The act of positioning the cartridge, usually by
the magazine, in line with the chamber in preparation for
chambering (Figure 30).
Chambering. Movement of the cartridge into the chamber
(Figure 31).
Locking (of cartridge in chamber). Depending on design,
the cartridge is locked in place, or chambered, simply by
closing the lever or bolt action or, with autoloaders, by letting
the slide spring forward.
Cocking. Cocking results in compression of the firing pin
spring and is accomplished by opening or closing the lever
or the bolt; or automatically, by autoloaders, on the second
and following shots.
Firing. Applying pressure to the trigger to release the
firing pin.
FIGURE 30—Feeding FIGURE 31—Chambering
Unlocking. Unlocking is the act of opening the action par-
tially or fully, which disconnects the striker and prevents the
rifle from firing.
Extraction. The means by which the cartridge head is
grasped or levered, thus drawing the case from the chamber.
Ejection. The “kicking out” of the fired case from the receiver,
or removing it by hand as with some single-shots.
All guns, except the blowback actions, operate within the
framework of these eight functions. Various rifles perform one
or more functions simultaneously, and not necessarily in the
sequence listed. In most cases, troubleshooting is a process
of identifying the function wherein a problem occurs, examin-
ing the part(s) that causes the function to occur, and locating
the part(s) that causes the problem.
Troubleshooting
Troubleshooting is probably 25 percent specific knowledge of
the particular rifle you’re working on and 75 percent common
sense. When troubleshooting, look for the four “Ds”—dirt,
dents, dings, and damage. Probably half of the functioning
problems encountered with rifles stem from dirt.
The first step in troubleshooting a rifle brought in with
mechanical problems is to interview your customer. He or
she can save you hours by answering questions concerning
when, how, under what conditions, etc., the problem first
occurred.
These are some questions you can ask your customer. What
is wrong with the gun? When did the problem(s) start? Did
the gun action jam before it started giving the current prob-
lem? Did someone drop the gun before the problem started?
Have there been similar problems before? If so, what was
the remedy? What does the customer think is wrong with
the gun? Ask any additional questions that come to mind as
the result of your initial questions. Look for obvious damage
such as broken, bent, or missing parts, which are quickly
visible to the trained eye.
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To be successful, you must develop an extensive working
knowledge of gun actions and the way they work. Then, it
will be relatively easy to spot the source of most mechanical
troubles.
If a customer interview and quick firearm examination don’t
reveal the problem source(s), it’s time to disassemble the gun
and give it a thorough washing in the degreasing tank.
Caution: Don’t place the wooden stock or other wood parts in
the degreasing tank. I know a supposedly reputable gun-
smith who submerged a Winchester M 94 in the tank. It took
all the varnish off the stock and made the wood very dark. If
it had been my gun, I would have demanded a new stock!
You may discover the problem(s) while disassembling the
gun. If you don’t, go over the gun again, looking closely for
broken, bent, or missing parts, screws, pins, etc. If nothing
is apparent, look for worn parts that may not be functioning
properly. Often trouble arises when a part that looks good
is actually worn to where it no longer reaches far enough to
do its job in the action. This is particularly true of extractors.
While they may look fine, they actually don’t grab the car-
tridge rim due to a weak spring or worn claws.
Extractor Problems
Extractors for many older guns are no longer available. You
can usually repair them by building them up with carbon
steel rod in either a gas torch weld or MIG weld. If using the
MIG, be sure to use the lowest possible heat as it’s all too
easy to overheat and carbonize small parts. (When steel
becomes carbonized, it crystallizes and loses most of its
strength.) After you build the offending part up in the worn
sections, file them to optimum shape, polish, and heat-treat.
It’s necessary to use carbon steel rod for building up extrac-
tors. Case-hardening doesn’t work well for extractors as they
wear through the hardened skin too soon.
Jammed Actions
A “jammed” action is a common problem that brings a cus-
tomer to the gun shop.
Warning: Never trust your customer to know if a gun is
unloaded. He or she may have removed all the cartridges
from the magazine, but one may remain in the chamber.
Your customer may believe he or she fired the cartridge, but
the jam may not have occurred until after a new cartridge
was inserted into the chamber.
Don’t accept a firing pin impression in the primer as absolute
proof the cartridge has been fired. The firing pin may have
hit hard enough to make an impression, but not hard enough
to set off the primer. You must take every precaution to
make sure the cartridge doesn’t accidentally discharge, and
of course, point the muzzle in a safe direction.
Safeties
Safeties made of cheap metal stampings often fail. Although
they seem to be functioning well, a strong trigger pull or
even a sharp jar or bump can bend them just enough to
cause them to fail. This is particularly true of older, lower-
grade .22 rimfire rifle safeties. It seems unconscionable to
me that gun makers would try to save a few pennies on the
metal in something as critical as the safety.
Holes and Pins
Often the problem will be a hole that has worn out of round
where a pin works in it. In such instances you can install a
new part (if one is available) or weld the hole shut and redrill
it. If it’s a larger hole, you can drill it oversize and insert a
bushing.
Warning: Of special importance, and highly dangerous, is
the situation where the firing pin sticks in the protruding
position in the bolt. This can, and frequently has, caused a
rifle to fire from an unlocked action when the shooter shoved
the bolt rapidly forward. In such an occurrence, the bolt will
violently expel from the rear of the gun. This is because only
the weight of the bolt and whatever bolt-retaining system is
in the gun are holding the bolt against the force of the gas
generated by the burning powder.
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The danger in such a situation is proportional to the power
of the cartridge being fired and the type of firearm action. In
a bolt-action where only a bolt retainer holds the bolt in a
gun chambered for .30–06 class, pressures are lethal. The
bolt would drive through one or more persons at high velocity.
Conversely, in a .22 rimfire firing the .22 short cartridge, the
weight of the bolt would largely dampen the force of the tiny
powder charge. A .22 long rifle cartridge will drive the aver-
age bolt hard enough to break the bolt retainer and severely
sting. Also, it could possibly break the fingers holding the
bolt, and the bolt could strike the body hard enough to do
severe damage.
On guns where the back of the receiver is enclosed, the bolt
will be held in the action. Still, in instances of the heaviest
loadings such as the magnum class of cartridges, the extreme
force of the powder gases could rupture the heaviest receiver
and cause severe or lethal damage.
The facts just given should make it abundantly clear that
you should guard against such accidents by always checking
for a firing pin that protrudes from the boltface.
Warning: The speed with which the bolt thrusts forward has
much to do with whether the gun fires if the bolt is closed
with the firing pin stuck in the protruding position. I have
deliberately belabored this point, as it is very dangerous.
Gunsmiths are most likely to come into contact with such
situations and be asked to fix such problems.
Rust
Rust is another major cause of malfunction. The best way to
remove rust is to use Naval Jelly.
Caution: Although Naval Jelly completely removes rust from
metal, it will also remove the bluing. Therefore, you shouldn’t
use Naval Jelly on surfaces that don’t take refinishing.
It’s necessary to wash the jelly from the gun and carefully oil
it after having used this process, as the metal is completely
clean and subject to rapid rusting all over again.
Note: The functions and troubleshooting topics we just dis-
cussed are general and apply to all firearms. Following is a
section that lists essential tools for performing troubleshooting
and repair as well as function and troubleshooting segments
geared to specific rifle action types.
Some Essential Tools
First of all, it’s important to have a good place to work. You
don’t need a fancy gun shop, as you can do most work quite
nicely in your basement. You do need a good workbench and
vise. The old blacksmith’s “Dogleg” or similar vise that has
raised jaws is the best style. It allows more access to the gun
(Figure 32).
A gun cradle is also very necessary for such work as cleaning
and scope mounting. I keep my gun cradle on a desk in my
den (Figure 33) where it’s clean and quiet.
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FIGURE 32—Shown is an old-style gunsmith/blacksmith vise withleather inserts to preventmarring work finishes.
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You should have a place beside the working vise where you
can lay out the tools you’ll likely need for the job at hand.
Figure 34 shows the tools laid out on my bench for a stock
bedding job, which includes changing the stock contour at
the wrist. I use the corncobs as handles on the wood rasps.
They work fine and have been used as file and rasp handles
ever since guns have been made in America.
FIGURE 33—A Gun Cradle.
FIGURE 34—Tools on the Workbench
You should also have a precision tool chest such as the one
shown in Figure 35. It sits atop a metal tool cabinet in my
shop. It holds such tools as micrometers, verniers, depth
gages, scribes, hole gages, telescoping gages, machine
squares, inletting chisels and gouges, and the many other
delicate, precision tools used by the gunsmith.
If at all possible, it’s good to have a place to sight in and test
the customer’s guns. You’ll need to make some arrangement
to shoot when testing guns, sighting in, and working up loads
for the customer’s guns. I’m fortunate enough to have a few
acres along the bank of the Potomac where there’s a 300 yard
range available near one of my workbenches. It’s also nice
(but not required) to have a chronograph available to help in
determining the most efficient and accurate load when hand-
loading for custom work (Figure 36).
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FIGURE 35—The GerstnerMachinists Chest consists ofwood, so fine precision toolswon’t sweat as they do inmetal chests.
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Lever-actions: Function andTroubleshooting
Modern lever-actions are direct descendants of the Volcanic
rifle, introduced in 1855.The first Volcanic rifle
carried its powder charge in the base of a coni-
cal, hollowed-out bullet. A cardboard or cork
disc kept the powder and primer in place.
Because the “cartridge” had no gas seal, pow-
der and velocity were low and the rifle passed
into oblivion in 1857 (Figure 37).
FIGURE 36—Shown is a shooting bench in one of Mr. Wood’s shops with a rifle resting on sandbags, a spottingscope, and an Oehler M 35P chronograph for testing velocity.
FIGURE 37—These drawings show theVolcanic rifle (top) with its oddball car-tridge, and its successor, the Henry,which fired the world’s first metalliccartridge.
One of the Volcanic Company stockholders, a fellow named
Oliver Winchester, purchased the company’s patents. His
foreman, Tyler Henry, redesigned the Volcanic and created a
surprisingly modern-looking rifle that fired the first metallic
cartridge—a .44 caliber rimfire, also designed by Henry. (The
“H” on the head of Winchester rimfire cartridges is in honor
of Henry.) The .44 caliber rimfire rifle, known as the Henry
Repeater, played a major role in the winning of the West.
The basic Henry model evolved into a series of famous
Winchester lever-actions:
• The Model 66, chambered for the .44 Henry cartridge
• The Model 73, chambered for the .44/40 centerfire
• The Model 75, chambered for more powerful black
powder centerfires, such as the .45/75.
The year 1881 introduced the first Marlin lever-action. It was
chambered for the .45/70/405 government cartridge. Later,
John Moses Browning designed improved lever-actions, later
sold to Winchester. They introduced the lever-actions as the
Winchester Model 1885 (the first smokeless cartridge, the .33
WIN.); the Model 1894, which introduced the famous .30/30
cartridge (Figure 38); and the Model 1895.The latter differed
from its predecessors in that it incorporated a box-type
rather than a tubular magazine, and was perhaps the first
lever-action that could safely use pointed spitzer-type bullets.
The 1895 was the favorite rifle of Theodore Roosevelt and
was chambered for such powerful cartridges as the .30–06
and .405 WIN. The company discontinued it in 1931.
Other early manufacturers of U.S. lever-actions were
Spencer, Marlin, and Savage. Of these, the Winchester 94,
Savage 99, and the Marlin, in its original form plus a new
short-action design, are still in production and chambered
for centerfire cartridges.
Most lever-actions utilize a tubular magazine feeding either
through the buttstock for .22 rimfire rounds or from a tube
mounted under the barrel for centerfire cartridges. Others,
using relatively powerful centerfire cartridges, employ a box-
type magazine. These include the Winchester 88, Sako
Finnwolf, and Savage 99.
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The Sequence of the Eight Functions inPopular Lever-action Rifles
The Winchester 94, Marlin 336, and the Savage 99 are the
most popular centerfire, lever-action rifles in use today. In
this section, we’ll relate the eight functions of rifle actions to
the operation of the Winchester 94, the Marlin 336, and the
Savage 99.
Winchester 94 and Marlin 336
First, let’s discuss the Winchester 94 and the Marlin 336. In
these rifles, the rifle (1) UNLOCKS as the lever is pushed
down. If a cartridge is in the chamber, it’s (2) EXTRACTED,
and (3) EJECTED. While the breech bolt moves backward, it
simultaneously cams the hammer back and down until the
hammer sears engage the trigger, thus (4) COCKING the rifle
on the opening of the action. Also, as the lever moves down,
FIGURE 38—This is the famous Winchester Model 1894. The cutaway view shows the rifle loaded.
a cartridge moves from the tubular magazine by spring com-
pression onto the lifter or “carrier” platform, aligning it with
the chamber (5) FEEDING.
When the lever is raised, the bolt moves forward, strips the
cartridge off the lifter, and carries it up into the chamber,
thus accomplishing (6) CHAMBERING. After the lever is fully
raised and flushed with the receiver, the action is (7) LOCKED
and the trigger can be pulled, thus (8) FIRING the rifle.
Figures 39–41 depict the inner workings of a modern lever-
action, the Marlin Model 336.
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FIGURE 39—With the rifle loaded and cocked,pulling the trigger releases the upper part of the trig-ger from the notch in the hammer. The hammer thenmoves forward and strikes the firing pin, detonatingthe cartridge. (Drawing courtesy of Complete Book of
Rifles and Shotguns by Jack O’Connor)
FIGURE 40—When the lever is pushed forward, thelocking bolt moves downward, disengaging from thebolt. The tip engages a slot in the bolt and movesthe bolt to the rear. As the bolt moves backward, anextractor hook pulls the fired case out from thechamber to a point where the spring-loaded ejectorkicks out the case. At the same time, the magazinespring forces a cartridge onto the carrier. The levercompletes its outward arc and the carrier and car-tridge start moving up. (Drawing courtesy of
Complete Book of Rifles and Shotguns by Jack
O’Connor)
FIGURE 41—As the lever returns to its original posi-tion, it first engages a pin on the carrier rocker,which cams the carrier into loading position. As thelever continues moving toward “close,” its tip pushesinto the bolt slot, moving the bolt forward and cham-bering the cartridge. When the lever fully returns, thelocking bolt rises to match the notch in the bolt, thusaligning the safety firing pin (see first drawing). Therifle can now be fired. (Drawing courtesy of Complete
Book of Rifles and Shotguns by Jack O’Connor)
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The Savage 99
In the Savage 99, the operation sequence of the eight func-
tions varies only because the Savage is cocked on the closing
of the action, while the Winchester and Marlin cock on opening
(Figures 42 and 43).
FIGURE 42—The Savage Model 99, Modern Version (Photo supplied by Reinhart Fajen, Inc.)
FIGURE 43—Shown is the cutaway view of the original Savage Model 1899. The top view shows the lever in theforward position and the bottom view with the lever closed. The design of contemporary Model 99s is essentiallythe same.
How Lever-actions Lock Up
The Winchester and Marlin rifles utilize a vertical rising block
arrangement for lockup. As the breech closes, the locking
block rises up to lock the bolt at the rear.
In the Savage 99, the shoulder at the rear of
the breech block wedges up against a corre-
sponding shoulder at the top rear of the action
when the lever closes (Figure 44). The breech
block also bears snugly against the sides of the
receiver. When the fit is perfect, as is usually
the case in newer 99s, the result is an enor-
mously strong action.
Most of the cheaper .22 caliber rimfire lever-actions lock up
by simple overbalanced camming. Closing the lever exerts
sufficient force against the cartridge head to achieve a satis-
factory seal. Chamber pressures are so low that not much
locking strength is needed.
Drawbacks of Lever-actions
Inadequate lock-up surface and inadequate strength are
characteristics of the older lever-action designs and even of
the newer configurations, such as the current Winchester 94
and Marlin 336 compared to most modern bolt-actions.
The older lever-actions with tubular magazines are limited to
flat-nosed bullets because of the danger of recoil causing the
point of one bullet to explode the primer of the next cartridge
in line. As most lever-actions lock up at the rear, cases have
a habit of stretching, making frequent trimming a must for
the reloader.
Troubleshooting Lever-actions
Dented Tubes
Lever-actions almost always have the magazine in a tube
located under the barrel. This tube often gets dented to the
point where the follower can’t push past the dent. The fix is
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FIGURE 44—When the lever is closed on aSavage Model 99, the breech block rises andwedges into position against the shoulder insidethe receiver.
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to drive a rod with a slight radius on the leading edge (which
is just under the inside tube diameter) down the tube to
push out the dent. Clean the tube thoroughly with a wire
brush to remove all rust and dirt. Then, turn a short section
of rod to a diameter about .001 under the I.D. of the tube
and push it to the dent and tap the dent against the rod with
a hammer until the dent disappears. Finally, grease the mag-
azine tube inside with a rust preventive before assembling
the spring and follower in the tube (Figure 45).
FIGURE 45—Exploded View of a Lever-action Rifle
Headspace Problems
Another common problem with lever guns is headspace. As
lever guns lock up at the rear of the action, there’s a great
tendency for the sides of the action to stretch. This is espe-
cially so when the shooter uses heavy loads. Although such
loads are within the pressure capacity of the action as indi-
vidual rounds, they tend to gradually lengthen the action
over extended periods of use.
Sometimes there’s excessive headspace in Winchesters that
lock up by lugs running inside mortises cut into the side
walls of the action. You can correct this by MIG welding a
ridge of metal up the sides of the lug where it bears upon
the mortise. Then, mill the welds down to the proper thick-
ness to correct the headspace problem.
Note: If you don’t have a milling machine, you can use a drill
press with a compound vise as a milling machine. Or, you
can smooth up the added metal by rough grinding on a
bench grinder and finish grinding with a small grinding
wheel set into the chuck of your drill press.
Place two guide fingers on the original surface between the
built-up sections to keep the part aligned while being ground.
Also, set a guide bar to hold the alignment from the back
surface of the lug. Whatever method you use, it’s necessary
to use a dial indicator to ensure there’s no taper in the lug.
It’s also necessary to measure the ground surface of the lug to
maintain the proper headspace. You must have established
just how much to move the bolt forward to correct the head-
space problem before starting the operation.
I’ve heard of adding a heavy chrome plating to the lug to
correct headspace. I’ve not tried this, but I pass it along for
consideration on the older guns where no replacement parts
are available. Always be sure you’re safety conscious in your
repairs.
Cracked Side Walls
On a lever-action, the side walls are the restraining force for
the pressures generated when firing.
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Warning: Always check the side walls of the action on guns
that have developed excessive headspace for cracks. The steel
used in most lever-action rifles is soft enough that it will
usually stretch considerably before cracking. On some rare
occasions, both Winchester and Marlin lever-action rifles are
said to have developed cracks in the side walls. I have never
personally found such a gun, but I did see a wrecked M 94
that let go on the left side of the action. A part of the surface
where the side wall separated rusted in a way that indicated
it had cracked long enough to rust before it let go. The shooter
didn’t sustain serious injuries. Fortunately, he was a left-
handed shooter, and the explosive force went away from him.
Had the shooter been firing the rifle from his right shoulder,
it’s quite likely he would have sustained serious injuries, if
not been killed, by the breech bolt, which no one ever found.
It’s a good idea to magnaflux any lever-action that has devel-
oped excessive headspace to check for hidden flaws within
the side walls. We’ll describe magnafluxing in detail later in
the course.
Some years ago, Savage brought out a bolt-action rifle cham-
bered for the .30-30 WIN. cartridge. This bolt-action rifle was
stronger than the lever-actions, and there were cartridges
made up especially for the bolt-action Savages in order to get
additional power from these rifles. While these “hot loads”
were clearly marked for bolt-action rifles, sometimes they got
mixed in with regular .30-30 loads and found their way into
lever-action rifles, which weren’t intended to withstand the
higher pressures. I don’t know of these loads blowing an
action, but there were quite a few actions around that sud-
denly developed excessive headspace at the time.
I also remember some customers who dropped by to ask if it
was possible to reload cartridges to the bolt-action Savage
pressures and use them in their Marlin and Winchester lever
guns. I believe the Marlin M 336 to be quite a bit stronger
than the older, square-bolt guns. It might be safe to make up
loads with a few more grains of powder using 150 grain flat-
point bullets for a flatter shooting load in the 336. However, I
would never recommend this to anyone or tell them it’s a safe
practice. In fact, I recommended against this hot loading, but
two of these same persons later ended up with headspace
problems in their lever-action .30-30s. I guess it’s pretty hard
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for some to admit they used cartridges not intended for their
guns, and which they were warned about using to get more
power. I have taken the time and space to tell this story to
point out that you should never trust people to follow your
recommendations even when they ask for and seemingly
respect your opinion.
The gunsmith is a respected authority, so you must be very
careful in what you say. Folks will feel you’re being conserva-
tive and think they’re allowing for your overcautious answers
in doing as they wish. They might try to use your advice,
even though you recommend against their plans, to justify
their acts.
Sometimes it can be downright scary, as in the following
example about a Remington M 788 in .30-30. This is a strong
action that can be loaded to .30-06 pressures; the action is
too short to accommodate the .30-06 cartridge. However, it’s
chambered in calibers that generate .30-06 pressures and in
this action, the .30-30, with judicious selection of powders,
can be safely loaded to .300 Savage velocities. Shortly after
the idea that the .30-30 could be loaded to 2,500 fps for use
in the Rem. M 788, one of my neighbors stopped by and
asked if it would be all right to load the Hodgdon BL-C (2)
loading. Such a loading gave 2,500 fps with a 150 grain
bullet in the Rem. M 788, in his Savage .30-30 rifle. He
reminded me that I had told his buddy that the Savage was
a lot stronger than the Marlin lever gun when his buddy
asked if it was safe to load the 2,300 fps Savage load in the
Marlin. Since his buddy had gotten by with using the hotter
load against my recommendation in the Marlin M 336, it
surely must be safe to use the .300 Savage class load in his
Savage .30-30.
Now get this: I told him that I had plainly told his buddy that
it was unsafe to load the Savage load for use in the Marlin.
His answer was, “Yeah, but you didn’t scream when he men-
tioned the loading, and we sorta figure if it’s really dangerous
you’ll scream when you hear the load.” This should illustrate
how careful you need to be when dealing with untrained
shooters. (Actually, previous to this incident, I had consid-
ered the neighbor to be a fairly accomplished and competent
reloader.) I will never make that mistake again. So this time I
screamed! I emphatically told him that the M 788 .30-30 load
82
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used in his Savage bolt-action would in all probability blow
his head off. I haven’t heard of this customer being seriously
injured, so I assume he took my warning.
Faulty Ammunition
Failure to fire can stem from faulty ammunition. This is
common with reloads in which the primer has been set a
bit too deep into the case.
Firing Pins and Springs
A very frequent cause of failure to fire in any type action is a
weakened hammer or firing pin spring. You can easily solve
this by installing a new spring.
Another common problem with Winchesters is firing pin wear
in which the firing pin is both shortened by wear and by the
hammer end being peened shorter from years of firing. Dirt
and crud in the firing pin assembly, and sometimes ahead
of the hammer, can slow the fall of the hammer so it doesn’t
strike the primer hard enough to fire.
An older Winchester or Marlin lever-action has more value as
a collector’s item than as a hunting arm, if it has mechanical
problems. Such guns can sell “as is” for more than the cost
of a new hunting rifle if rebarreling or rebluing hasn’t ruined
them. If you need a hunting rifle, a wise idea is to sell the
old-timer and buy a new modern hunting rifle with a part of
the proceeds. If the oldie is a keepsake or heirloom, don’t try
to have it repaired in any way that will modify it and lower
its value as a collector item. Just retire it to a place of honor
on the wall and use a newer, less valuable, gun for hunting.
We included the previous information in the lever-action section
since a large number of the deer rifles in use are collector
items. The information regarding older rifles is equally appli-
cable to other type actions that have become valuable.
Oversize Firing Hole
A problem common to many types of older rifles is an over-
size firing hole in the bolt face. This often causes difficulty in
extraction due to the primer being forced back into the bolt
face. It also allows the unsupported primer to rupture and
hit the shooter in the face with a blast of hot gas, which can
be extremely hazardous to the eyes. There are two common
solutions to this problem. One is to weld the firing pin hole
shut and redrill the hole to the proper size. I don’t particularly
like this method, as it requires heat-treating the bolt again,
and repeated heating of carbon steel weakens it. The method
I prefer is to drill the bolt face and tap a 5/16 inch thread into
it. Then, insert a section of heat-treated Allen screw into it
and clean the ends up so they’re flush with the bolt surfaces.
After you insert the threaded piece, drill it to the proper size,
and smooth it up, “stake” it with a punch on the inside sur-
face so it can’t move in the threads. This will hold it perma-
nently in place, but in the event that it becomes worn in the
future, it is easy to remove the plug and insert and redrill
another one.
Final Thoughts on Lever-actions
Unusually superior rifles stand out from others of their kind.
The first repeating rifles were lever-actions, and they’ve
earned their place in the firearms hall of fame. My candidate
for the outstanding lever-action rifle is of much more recent
date. It’s the Marlin .444S rifle, chambered for the .444
Marlin Cartridge, which gives the shooter who needs a short,
reasonably light and fast-handling rifle a lot of knockdown
power for hunting critters in the woods (Figure 46).
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FIGURE 46—The .444 Marlin rifle with Leupold Vari-X III 1.5 � 5 scope is a fine brush gun for most any NorthAmerican game at moderate ranges.
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The Savage M 99 is a close second candidate for honors in
the lever-action class. It’s an excellent rifle with sufficient
power. The Marlin lever-action rifle currently being made in
caliber .45-70 is also a splendid woods rifle, but it has
caused cartridges to be made that, if fired in the Springfield
Trapdoor rifles, would ruin the rifles. As with the hot .30-30
loads, I discourage such loadings for the very real danger
they present to the unknowing and the fool.
The Winchester M71 is a real powerhouse among lever-
actions. If we rated lever-actions solely on power, it would
be the hands-down favorite, chambered for the .348 Win.
Cartridge. The M71 is too heavy for most folks to carry
easily or comfortably.
The Savage 99 is an internal hammer gun with a rotary mag-
azine that’s an excellent design. It usually feeds flawlessly,
but is subject to problems if dirt gets into it. The most com-
mon dirt is pieces of twig that find their way into the action
if it’s cycled while standing in brush. The lockup is different
from most lever-actions because it locks by camming a
“hump” into the back of the breech recess. This is a very
strong lockup. The only trouble I know of with these is that if
the shooter shoots hot loads, the action may sometimes be
difficult to open. If this occurs, strike the top of the breech
block sharply with a wooden mallet. If you’re in the woods,
use a length of wood to tap the block down until free. Never
try to force it open by pulling harder on the lever; you’ll only
succeed in disengaging the lever from the breech block.
The Winchester M 88 and the Browning BLR rifles use a
lever to operate the action. But the lockup is like the multilug
bolt actions and should be treated in the manner described
under bolt-action troubleshooting.
The Marlin M 39 and 39-A are two longtime favorites among
.22 centerfires, and recently the Winchester M9422 has
taken its place among lever-action favorites. Troubleshooting
these models is as with other lever-action rifles.
It’s necessary to mention the Winchester M 250. This ham-
merless lever-action .22 rimfire has what seems to me to be
very poor construction, due to a locking mechanism that’s
similar in principle to the Model 12 shotgun. If it were as
tough and durable as the Model 12, it would be a dandy.
However, the locking plate, which cams into the locking
recess, seems to peen the softer receiver metal away until it
develops excessive headspace. The fix is to install a hardened
pin or weld with a hard alloy rod behind the shoulder to
maintain the locking position. This rifle has other problems
in a number of parts that are too lightly constructed of sheet
metal, and in its cam pin, which is riveted into the locking
plate arm and wears loose with continued use. There’s no good
fix except replacement of the entire locking plate assembly.
Lever-action rifles, with the notable exceptions of the Savage
M 99 and the Winchester M 88, are of only moderate accura-
cy. (I frankly don’t know how well the Browning BLR shoots
as I have never tested one.) Recently, makers of lever-actions
have changed the attachment of the magazine tubes to the
barrel and eliminated the main cause of their poor accuracy.
You can greatly improve the accuracy for some Winchester
M 94 rifles by adjusting the attachment of the forearm and
magazine tube. There’s no ironclad rule as to whether to
loosen or tighten them. Try both loosening and tightening
them to increase accuracy. Sometimes inserting a section of
Popsicle stick on each side of the forearm will result in greatly
improved accuracy. In other instances, exactly the same
treatment of another rifle will show no result whatsoever or
actually decrease accuracy.
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Self-Check 6
Indicate whether the following statements are True or False.
_____ 1. You should always check the side walls of the action for cracks on guns that havedeveloped excessive headspace.
_____ 2. Modern lever-actions are direct descendants of the Volcanic rifle introduced in 1855.
_____ 3. In older lever-actions with tubular magazines, you should use flat-nosed bullets.
_____ 4. The Winchester M 88 and Browning BLR are lever-actions that house the same locking mechanism as other lever guns.
_____ 5. In magazine-fed rifles, one of the first things to check in feeding problems is dentsin the magazine.
Check your answers with those on page 130.
PUMP-ACTIONS: FUNCTION ANDTROUBLESHOOTING
The Sequence of the Eight Functions in Pump-action (Slide-action) Rifles
In the previous section, we discussed the sequence of the
eight functions in lever-action rifles. In this section, we’ll dis-
cuss the eight functions in pump-action rifles. You move the
bolt or breech block in such rifles forward or back by manip-
ulating the forearm. The forearm is attached to the bolt
assembly by one or two action bars, depending on the
firearm (Figure 47).
The sequence in the Remington Model 760, and most pumps,
follows.
As the forearm is pulled to the rear (after firing or manual
release of the action lock), it (1) UNLOCKS the action, then
(2) EXTRACTS, and at the end of the movement (3) EJECTS
the cartridge. As the rearward bolt travel stops, the hammer
is (4) COCKED. At this point the magazine has accomplished
(5) FEEDING by lifting the cartridge into the uppermost posi-
tion. When the forearm moves forward, the bolt strips the
cartridge from the magazine and pushes it into the chamber,
thus accomplishing (6) CHAMBERING. In the final forward
motion, the bolt rotates and the lugs are engaged, thus
accomplishing (7) LOCKING. The rifle is now ready for (8)
FIRING. Figures 48–50 illustrate the sequence.
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FIGURE 47—The Remington 760 “Gamemaster” and its newer versions are the only slide-action rifles to handlesuch high-intensity cartridges as the .30/06, .270, .308., etc.
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FIGURE 48—As the forearm moves to the rear, the action bar and bolt assembly are pushed backward, simultane-ously pressing the hammer downward and ejecting the fired case. A “loop” spring with a claw in the face of thebolt (see small left-hand drawing) hooks under the rim of the cartridge and extracts it from the chamber. Whenthe case clears the chamber, the ejector spring in the bolt flips the case clear. The magazine spring then pushes anew cartridge upward. (Drawing courtesy of Complete Book of Rifles and Shotguns by Jack O’Connor)
FIGURE 49—When the forearm is pushed forward, the action bar and bolt assembly move forward, stripping thecartridge from the magazine and into the chamber. The notch in the sear retains the hammer in the cocked posi-tion. As the bolt continues moving forward, the bolt threads contact the locking lugs (see small illustration). Acam on the carrier engages a curved slot in the bolt, causing the bolt to turn and thread into the locking lugs.(Drawing courtesy of Complete Book of Rifles and Shotguns by Jack O’Connor)
How Pump-actions Lock Up
The Remington 760, essentially a Mauser turning-bolt
design, has a multiple-lug lockup. As the bolt is seated, it
turns, locking the lugs in the barrel extension. Other pump-
actions lock up in a variety of different ways. The old
Remington 14 and 141 employed a single lug lockup similar
to the Krag-Jorgenson, which, because of the one-side sup-
port, limited the action to pressures of not higher than
42,000 psi (.30-30 class).
Troubleshooting Pump-actions
The pump-action rifle is an offshoot of the popular pump
shotguns (Figure 51). Shooters who regularly used and liked
the pump shotgun wanted a rifle that handled and func-
tioned like the shotgun they were familiar with for their deer
hunting. The first really “serious” centerfire pump rifle was
the Remington Model 141 chambered for the .30 Remington,
.32 Remington, and .35 Remington cartridges. The .35
Remington was by far the most popular. The M141 had a
spiral magazine under the barrel that prevented the points
of the pointed bullets from bearing on the primer of the
round ahead of it. This major improvement allowed the
use of bullets of better ballistic coefficient.
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FIGURE 50—Pulling the trigger causes the trigger sear to disengage from the notch on the hammer, permittingthe mainspring to drive the firing pin against the cartridge primer. (In the interest of clarity, we don’t show thesafety lock and disconnector in this illustration.) (Drawing courtesy of Complete Book of Rifles and Shotguns by
Jack O’Connor)
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As mentioned, the Remington M 760 and the Savage M 30
arrived on the scene to adequately fill the needs of pump rifle
devotees. The Remington 760 is a rotary bolt design that’s
capable of withstanding heavy chamberings of .270 WIN. and
.30-06 calibers. Like the Winchester M 88 lever-action rifle,
you should service the Remington 760 using the instructions
for bolt-actions.
FIGURE 51—Exploded View of a Pump-action Rifle
Magazine Cutoff Problems
The most frequent problem with pump rifles is the tubular
magazine cutoff’s failure to catch the second cartridge after
the lifter picks up the first one. An equally frequent problem
is its failure to release a cartridge to the lifter. Both malfunc-
tions are almost invariably traceable to our old villains: accu-
mulated dirt and crud. It always seemed that pump guns
were the most vulnerable of all action types to the ravages of
crud.
Annual Cleaning Required
The owner of a pump gun should do an annual action
cleanup using a pressurized degreaser/cleaner such as Gun
Scrubber. To clean a pump action, insert the extension spout
into the action and move it about while spraying the solvent.
Allow the solvent to soften the accumulated crud a few min-
utes, and again wash the action out with the spray. This
should eliminate about 95 percent of the problems you would
have encountered with pump-action rifles.
.22 Rimfire Pump Rifles
In addition to the centerfire pump-action rifles just listed,
there are many .22 rimfire pump rifles. Perhaps the best of
them are the Winchester Model 62 hammer model and its
cousin, the model 61 hammerless pump.
The Remington hammerless models 241 and 121 are also
excellent rifles. Of more recent production is the Rossi gallery
rifle, which seems to be an exact copy of the Winchester
model 62 hammer gun. These are all excellent guns, but my
favorite and candidate for all-time great .22 RF pump rifle is
the long-obsolete Winchester model 61 hammerless rifle. It’s
capable of excellent accuracy, far above the level of accuracy
demonstrated by the other guns mentioned. I have a model
61 that gives 3/4 inch 50 yard groups. I got it back in the late
1940s mounted with a Weaver J4 scope, which was then
state of the art. It was deadly squirrel medicine. This model
gets my vote for the all-time outstanding .22 RF pump gun.
The M 62 is a close second (Figure 52).
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Problems Associated with Takedown Models
In addition to the usual problems brought on by accumulated
crud, the aforementioned Winchester rifles suffer from being
takedown models. They can separate at the action, one side
remaining on the stock section and the other side of the
action staying with the barrel and magazine. The separation
leaves the entire working parts section of the action exposed
to rough handling and even more dirt. Then, damage occurs
if the sections aren’t put together properly. They also tend to
work loose at the takedown joints.
Dented Tubes
The information on dents and dings and on cleaning and
greasing the inside of tubular magazines, given in the lever
gun section, is also applicable to pump-action rifles because
they’re tubular magazine rifles. Sometimes the Remingtons
would have a bit of trouble with the shell lifter getting stuck
or not starting the cartridge into the chamber properly.
All in all, there are very few problems with any specific pump
rifles of which I’m aware that would require special notice.
So, the general rules of rifle troubleshooting presented earlier
apply.
Bolt-action Rifles: Function andTroubleshooting
Probably the first true turn-bolt rifle was the Needle gun
developed by Dreyse in the late 1830s. It didn’t shoot nee-
dles, but was so named because of its long, needlelike firing
pin that protruded from the rear of the bolt when cocked.
FIGURE 52—The Winchester model 62 hammer model, one of the first pump .22 rifles, is a collector’s item today.
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The rifle’s paper cartridges and leaky ignition system were a
drawback. Shooters preferred to fire from the hip and thus
escape the blowback and black face that could do as much
damage as the business end of the arm.
The first really successful bolt-action design was the 11mm
Mauser single-shot of 1871, which employed a true turning-
bolt design (Figure 53). In 1884, it was equipped with an
under-barrel tubular magazine, holding eight .43-caliber
Mauser cartridges.
The next important step in the evolution of the bolt-action
was the Spanish 1893 Mauser. It was developed about the
same time as the Krag Jorgenson rifle of Norway, which the
U.S. military adopted in 1892.The Mauser used a staggered
column clip magazine as opposed to the Krag’s ungainly box
magazine, which had to be loaded with single cartridges. The
Krag had only one locking lug while the Mauser had two,
thus providing superior strength.
The Model 1893 Mauser was the forerunner of the greatest
individual firearm design of all time: the Model 98 (Figure 54).
This model incorporated the two front-locking lugs of the 93,
but added an additional locking lug toward the rear of the
action for extra strength. Also, the cocking piece was shrouded
to protect the shooter from escaping gas.
94
FIGURE 53—Shown are cutaway views of the Mauser 11mm with the under-the-barrel tubular magazine added in 1884.
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The only other early turn-bolt rifle of any consequence was
the Mannlicher, developed in Austria, which incorporated a
spool-type magazine similar to that later used in the Savage
95 and Model 99. The bolt handle was positioned ahead of
the receiver bridge, necessitating a split bridge, which, when
scopes were later developed, made mounting them difficult.
How the Eight Basic Functions Apply inModern Bolt-action Rifles
For purposes of discussion, we’ll consider the Model 700
Remington and assume that the rifle has just been fired.
Refer to Figures 55 through 59 as we discuss the functions.
FIGURE 54—The Swedish M40 Variation of the 1898 Mauser, Caliber 8 �� 63mm
FIGURE 55—Model 700 Remington (Drawing courtesy of Complete Book of Rifles and Shotguns by Jack O’Connor)
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FIGURE 57—Japanese service rifle (Arisaka). The illustration shows details of a mechanism with the rifle cockedand ready to fire. Note the position of the trigger sears and the unique mainspring—positioned inside the hollowfiring pin section.
FIGURE 58—The Italian Carcano 6.5mm carbine is identical to the rifle except that the barrel is 21 inches long,10 inches shorter than on the rifle.
FIGURE 59—Shown is the Carcano cutaway view illustrating the action open and with loaded clip magazine. Thisfirearm cocks on closing like the early Mausers.
FIGURE 56—6.5mm Japanese Arisaka, Model 38
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1. As the bolt handle is raised, the bolt lugs rotate and
(1) UNLOCKING takes place. A notch at the bottom of
the bolt handle engages simultaneously and raises a
spur on the firing pin head, thus pushing the firing pin
to the rear and compressing the mainspring.
2. When the bolt assembly is drawn back, (2) EXTRACTION
occurs as the case is drawn from the chamber. A circular
spring in the face of the bolt tightens the claw, gripping
the case head tightly. When the fired case clears the
chamber, the spring-loaded ejector (3) EJECTS the spent
cartridge. The magazine spring forces the next cartridge
up into loading position (4) FEEDING.
3. As the bolt moves forward, it strips the cartridge from
the magazine, (5) CHAMBERING it. When the bolt
thrusts fully forward and turns down, the lugs engage
the chamber recesses, accomplishing (6) LOCKING. At
the same time, the sear engages the firing pin head,
(7) COCKING the rifle.
4. When a shooter squeezes the trigger, it disengages the
sear from the notch on the firing pin head. The main-
spring thrusts the firing pin forward, (8) FIRING the
cartridge.
Lock-up Systems, Bolt-action Rifles
Bolt-actions lock up by means of lugs on the bolt face, which
when rotated by the action of the bolt handle, engage recesses
in the chamber (Figure 60). The Krag had one locking lug;
the 93 and 98 Mausers have two locking lugs. The Krag was
designed to contain pressures up to about 40,000 psi, the 98
for about the same pressure level. However, if the steel is of
the proper hardness, good 98 actions can easily accommo-
date pressures up to 55,000 psi—the maximum safe limit for
today’s magnum cartridges.
Multiple Locking Systems
As cartridges became more powerful, the need for a stronger
system became paramount. The solution was obviously a
system that employed multiple locking lugs. This adds to
the amount of bolt-to-chamber locking or shearing area and,
theoretically at least, increases strength. We say theoretically
because, if all lug surfaces don’t bear fully and equally, the
action weakens and accuracy suffers. You can check the lug
surfaces by applying Prussian blue to the lug areas and then
checking the receiver recesses for color.
At least one modern bolt-action of super-magnum persuasion
employs the front-locking multiple-lug principle—the
Weatherby Mark V, with nine small lugs (Figure 61). The
Remington 788 and Schultz & Larsen Finnish rifle, both
obsolete, used a rear-locking, multiple-lug setup.
In the Weatherby, the lugs are the same diameter as the bolt
and the bolt is the same size as the inside of the receiver.
The cartridge head is fully enclosed and
the action is slick and smooth.
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FIGURE 60—Shown are three types of bolt-actionlock-up systems. The top drawing illustrates the con-ventional Mauser two-lug lock-up, with the lugs onthe bolt engaging recesses in the receiver ring. Themiddle drawing shows the single-lug lock-up used onthe Krag-Jorgenson, some early side-actions, andother rifles. Support at one side only often changesbullet impact drastically when cartridges differentfrom those used in zeroing are fired. The bottomdrawing illustrates the multiple lugs, which serve as“threads.” When all lugs bear evenly, the action isstronger than the two-lug design.
FIGURE 61—Pictured is a close-up of theWeatherby Mark V action showing multiplesmall lugs and recesses in the receiver.
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The multiple-lug design (or interrupted thread design), while
primarily found on newer rifles, actually goes back to an
earlier period. The system was probably first introduced
by Charles Newton, a turn-of-the-century firearms and
cartridge designer, in the rifles he made for his then- and
still-impressive Newton cartridges. Not only was the multiple-
lug concept exceedingly expensive from a production stand-
point, but the design in Newton rifles was an entire disaster.
A shooter could fire the rifle without locking the bolt. The
maiming of a number of shooters by bolts flying backward
caused the discontinuation of the arm.
Other early rifles, notably the Remington pump and some
autoloaders, used multiple lugs. Today rifles of lever, pump,
and auto-loading design use the system.
An advantage of the multiple-lug design in bolt-actions is
short bolt lift. The standard Mauser action requires a 90
degree lift to open the action. Adding additional lugs at
the front or rear of the bolt shortens the bolt lift to 45-60
degrees. This provides faster repeat shots and ample clear-
ance between the bolt handle and the scope bell.
Gas Venting, Bolt-action Rifles
Since the invention of the self-contained cartridge, the need
has existed to provide the shooter with protection against
escaping gases usually caused by leaky primers or failure
(rupturing) of the brass cartridge. Such escaping gas or
blowback, if not diverted, could travel down the length of
the firing pin and directly into the eye of the shooter.
Therefore, gas ports are always engineered into the
modern rifle (Figure 62).
FIGURE 62—Shown are gas escape ports. Early Springfields(1) had only one gas port; later models incorporated a second port, similar to the Enfield (2). Excess gas is thenexhausted through the ports. The Mauser 98 left little roomfor improvement. Two gas ports, oblong shaped, appear onthe left side of the bolt and extend into the firing pin hole.While most escaping gases exit through these apertures,any gases traveling along the outside of the bolt woulddivert to the side by the shieldlike design of the forward bolt sleeve.
Such relatively high-pressure actions as the Weatherby utilize
a number of gas ports along the side of the bolt (Figure 63).
Safeties on Bolt-action Rifles
There are generally three types of safeties employed:
1. Those that disconnect the striker as in the Weatherbys
2. Those that lock the striker, as in the original and
commercial Mausers
3. Those that merely lock the trigger and prevent its
being pulled.
Manufacturing Bolt-action Rifles
The receivers in older rifles were usually forged from solid
steel billets. Current production methods incorporate invest-
ment castings in which the metal is formed to tolerances that
eliminate practically all machining and millwork. The process
is cheaper and the molecular structure of the steel is such that
investment castings are much stronger than those forged
from metal blocks. No internal stress is set up within the
receiver, such as that caused by forging and metalworking.
Today there are basically three different lengths of bolt-action
designs—short, medium, and “standard”—plus the compara-
tively new magnum-length action (Figure 64).
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FIGURE 63—Notice theWeatherby Mark V,showing triple gas portsin the side of the bolt.
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Troubleshooting Bolt-action Rifles
The bolt-action is the most trouble free of all the actions,
with the possible exception of the falling block single-action.
Still, problems occur regularly with even the bolt-action.
First, of course, is our old friend, “accumulated crud.” In
the bolt-action, crud isn’t as serious as in other action types,
due to the greater camming action of the bolt and absence
of many small weak parts in the relatively simple bolt-action
(Figure 65).
FIGURE 64—Sako is but one ofmany manufacturers who makeessentially the same action indifferent lengths for specificlength cartridges. In addition to the three actions shown, Sako also makes a long magnum version.
Stuck Cases
Stuck cases are probably second in troubles with the bolt-
action, due in part to the higher pressures generated by
bolt-action loads and the fact that many bolt-action fans
reload. Reloaded cases tend to stick for several reasons. Chief
among them is that reloaded ammunition is generally loaded
to higher pressures than factory ammo. For example, if it
were not for the low number of cast-action Springfield rifles
chambered for the .30-06, the .30-06 factory loadings would
shoot a lot flatter. Also, the .270 WIN. would show little, if
any, advantage in trajectory over the .30-06. Hot loads tend
to make cases wear out much faster and to separate, leaving
part of the case in the chamber.
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FIGURE 65—Exploded View of a Bolt-action Rifle
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Note: You might not be familiar with all of the bolt-action
rifles that come into your shop. But don’t worry—I would
question the veracity of anyone who claimed to be familiar
with all of the bolt-actions available today. One has only to
look through the pages of the Shotgun News or a similar
publication to realize there are new bolt-actions appearing
every day. It’s truly impossible for the gunsmith or anyone
else to be familiar with all of the rifles available today. The
best you can hope for is to be familiar with the sporting rifles
available and the more common military conversions that are
most likely to appear at your shop.
As already mentioned, the bolt-action locks by turning lugs
into recesses cut into the action. There may be one or more
lugs extending to the front side of the bolt as in the Mauser
and similar actions such as the Springfield, Winchester M
70, Remington M 700, and many others. The lug can be
an interrupted screw thread at the front of the bolt or an
interrupted screw thread at the rear of the bolt as in the
Remington M 788. The lug can also be several medium-size
lugs on the front of the bolt as in the Browning BBR and
the Weatherby Mark V.
There are bolt-actions such as the Winchester M 67 .22 cal-
iber and similar rifles where the locking lug is the butt of
the bolt handle. Then there’s the Winchester M 52, which
has screw-adjustable headspace from an adjustable locking
face in the bolt handle. I could go on, but I think the point
is evident.
Common Causes of Problems
Problems with bolt-actions usually stem from crud, weak
springs, loose screws, broken firing pins, or firing pin screws.
Safeties, improperly converted to clear telescopes, are also
high on the list of bolt-action problems.
Extractor Problems
Broken, worn, or weakened extractors are also common
bolt-action problems, as are broken ejectors. You can easily
replace the Mauser-type extractors or you can weld up
and resharpen them if the claws are worn or broken. You
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must heat-treat them to harden them, so use carbon steel
that will harden as suggested in the section on general
troubleshooting.
Mauser-type ejectors are studs that run in a lengthwise slot
in the bolt. When the extractor pulls the fired case to the
ejection point, the ejector strikes the cartridge head and
knocks it loose from the grip of the extractor.
Remington and other bolt-actions that feature the enclosed
case head use a recessed, spring-loaded pin, which is inside
the ring-shaped extractor. The ring extractor holds the case
in place until it reaches the rear limit of travel of the bolt and
then the pin flips the case free of the action.
The Ruger M 77 uses a Mauser type extractor with a spring-
loaded, pin-type ejector. Some bolt-actions use twin claws set
into the sides of the bolt and held in place with a pin instead
of the extractor ring as with the Mauser and many others.
The principle is the same as the other claw types. Most bolt-
action extractors and ejectors will come under one of these
types.
As noted earlier, there are just too many different bolt-action
rifles to explain all of the variations in this size book.
Firing Pin Problems
Firing pins are sometimes broken in all types of actions and
the bolt-action firing pins are generally easier to replace. In
the military types, the rear of the bolt screws off so you can
pull out and easily replace the firing pin. They’re generally
held in place by the tension of the firing pin spring just as
they are in the Springfield and most other military rifles.
Warning: Exercise extreme caution when replacing a firing
pin. Make certain that a replaced firing pin doesn’t extend
too far into the chamber (in either the battery or retracted
position) or travel too far forward when struck by the striker.
A firing pin that extends too far forward will rupture the
primer and release hot powder gases into the rifle action.
Also, the firing pin may remain in the primer and prevent the
case from ejecting. The coil springs used in bolt-action rifles
are very durable, but occasionally one will become weakened
by the rifle having been allowed to sit cocked for too long a
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Rifles 105
period. The replacement is easy, but sometimes you have to
thrust a pin through a hole in the striker to hold the spring
while you screw on the rear of the bolt. The new spring may
seem too long, but will gradually shorten, or “set” as time
passes. Don’t shorten the replacement spring unless you
absolutely can’t get it into place.
Note: The bolt handle must remain in the cammed or “up”
position while you remove it from the rifle for cleaning and/
or other purposes. There should be a tiny detent to assure
this. If it slips and comes uncocked, you’ll have to rotate the
bolt handle to get the bolt back into the rifle. The rotation
operation usually requires a vise or some way to hold the
bolt firmly so that you can rotate the handle to cam the firing
pin back against the spring tension.
The U.S. M1917 Enfield rifle cocks on the closing stroke.
Most shooters don’t like this feature and will buy a kit to
convert the bolt to cock on the opening stroke when the bolt
handle is lifted. Installing the kit is a straightforward proce-
dure, but it’s very important to ensure that the cocking cam
won’t slip and let the firing pin come forward. If this occurs,
the bolt will close with the firing pin protruding into the
chamber. Here it will strike the primer of a round in the
chamber and possibly set it off without the bolt handle being
locked.
I experienced this once when I suddenly found I couldn’t
close the bolt on an Enfield that I had converted to cock on
the opening stroke with a kit sold for this purpose. I was
groundhog shooting one evening and when I fired at one pig,
another one popped up and made an excellent target. I threw
another round into the chamber and tried to get the bolt
closed. It wouldn’t close even when I tried to force it with the
bolt handle. I looked to see the problem and found that the
gun had come uncocked. I was trying to force the bolt closed
with the firing pin protruding into the primer of the round in
the chamber! When I saw what had happened and noticed the
fairly deep indentation the firing pin had made in the primer
of the loaded round, I felt the hair on my neck stand up. I
will never know what kept the rifle from firing, except that
possibly the spring was able to cushion the shock when the
bolt closed. I’m forever grateful that it didn’t fire because I
would have had a bolt through the head if it had. I’ve always
felt that “someone up there” was watching over me that day.
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Bolt-action Safeties
In my opinion, bolt-action safeties are the most positive of all
the different action types. The Mauser type has a lock that
cams down into the rear of the firing pin striker and makes
it impossible for the gun to fire without taking off the safety.
The Enfield, Springfield, and many others have the same
almost foolproof safety. The Winchester M 70 is also a very
safe type as are the Ruger and Browning.
When converting military rifles to sporters, it’s necessary to
change the original safeties so they won’t interfere with
mounting a scope. You can convert the Springfield and
Mauser safeties to clear a scope by either of the following
ways. You can weld on a safety lever at an angle to the
original or buy and install a safety conversion kit such as
that offered by Brownells.
Grease and Crud Build-up within the Bolt
One final problem with bolt-actions concerns grease and
crud build-up, which is usually not a major problem until
cold weather stiffens them up. You can avoid grease and
crud build-up by using a light machine oil in the rifle bolt.
Then you won’t miss that nice buck one cold morning when
your firing pin striker slows down from stiff grease and crud
and fails to strike the primer hard enough to fire the gun.
Final Thoughts on Bolt-actions
If I were to select one bolt-action as the all-time greatest, it
would have to be the Winchester Model 52 Sporter in caliber
.22 long-rifle rimfire (Figure 66). I have one, which when firing
Eley Match ammunition, will produce five shot groups meas-
uring about .140 inches over bullet diameter at 50 yards.
Semiautomatic Rifles
World War II did for the semiautomatic rifle what World War I
accomplished for the bolt-action repeater. Those accustomed to
bolt- and lever-actions gained respect for the semiautomatic
rifle through use of the M1 Garand and M1 carbine. Today
the “old” Garand is all but obsolete, yet it paved the way for
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Rifles 107
several centerfire (including magnum variety) semiautomatic
rifles plus a myriad of .22 rimfire designs.
Probably the first “example” of a true auto-loading design
was the brainchild of John Moses Browning. He mounted a
paddle to the front of a Winchester Model 73 rifle and linked
it to the lever mechanism. The force of gases exiting from the
muzzle pushed the paddle, thereby operating the 73’s lever
“automatically.” From this basic start, Browning eventually
invented several different types of semiautomatic mechanisms
that he incorporated in his shotgun and machine gun designs.
The difference between an auto-loading firearm and other
designs is the eight functions, only firing is performed
manually. The rifle performs the other seven automatically,
permitting the shooter to concern him or herself only with
aiming and squeezing the trigger. For this reason, semiauto-
matic sporting firearms, usually referred to by the misnomer
“automatics,” are quite popular. A succession of shots is
seldom necessary in the game field, but the relative ease of
operation and knowing those follow-up shots are there has
“sold” the self-loader to many hunters. There are three basic
groups of semiautomatic designs:
1. Gas-operated
2. Recoil-operated
3. Blowback
FIGURE 66—The Winchester M 52 Sporter is unquestionably the finest .22 rimfire rifle of all time. Notice its Leupold Vari-X III 4X compact scope—a truly fine rifle for both small game and targets.
Gas-operated Design
The most familiar type of selfloading or semiautomatic action
is the gas-operated, of which there are two subdivisions:
(1) the long-stroke system and (2) the short-stroke system.
The M1 Garand and the M1 carbine of World War II, both
gas-operated, are examples of each type (Figures 67, 68, and
69). The Garand uses a long-stroke system where gas vented
off near the muzzle activates a piston with a long operating
rod that in turn activates the action.
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FIGURE 67—U.S. Rifle Cal. .30 M1 Garand (Photo supplied by Reinhart Fajen, Inc.)
FIGURE 68—U.S. Carbine Cal. .30 M1
FIGURE 69—Operation of the U.S. Carbine M1. Unlike the Garand, gas vents into a cylinder midway down thebarrel. Cutaway shows the bullet just passing over the gas vent port. The action is still locked. Although Garandand M1 cartridges are of the same caliber, the cases and ballistics are vastly different.
Rifles 109
The M1 carbine and many modern auto loaders use the
short-stroke gas system. In the short-stroke gas system, the
gas vents through a port midway down the barrel and into a
gas cylinder where it activates a short-stroke piston moving
only about a quarter of an inch. The short movement of the
piston is transmitted to an operating rod or arm, which then
opens and operates the bolt.
In all gas-operated semiautomatic arms, the action opens
by the force of the explosion (gases), and closes by strong
springs compressed by the gas.
Recoil-operated Design
The second type of semiautomatic operation is by recoil, and
there are two types: long recoil and short recoil.
The long-recoil design has been in use for more than 50
years, and is a solid, dependable system, used primarily in
shotguns and pistols. (Centerfire rifle cartridges generate too
much pressure for the design principle.) A disadvantage is
the “double slam,” annoying to many shooters, when the
recoiling barrel adds a second jolt to the primary recoil.
The Long-recoil design. Long recoil is so called because the
barrel and bolt (breech block), securely locked together, recoil
farther than the length of the cartridge—usually three to four
inches. The bolt temporarily locks at the rear of the action
while the barrel, under the impetus of compressed springs,
moves forward. The fired case, secured to the breech bolt by
the extractor, ejects when the barrel starts its forward
motion. Upon return to battery (firing position), the barrel
trips a lever, which unlocks the breech bolt. The bolt then
moves forward, picking up a new cartridge and chambering
it as the bolt slams home (Figures 70 and 71).
In years past, Remington made several long-recoil operated
rifles, notably their Model 8 and Model 81.These arms were
distinguished by a heavy barrel shroud or sleeve that con-
tained the arresting mechanism into which the barrel recoiled.
Such an arrangement had a bad effect on accuracy. Another
drawback that led to the long recoil’s early demise, aside from
being difficult to work on and hard to keep operating, was
the fact that they were generally limited to medium-powered
.30-30 class ammunition. (The Model 81, however, was also
chambered for the .300 Savage, a more powerful cartridge
approximating early .30/06 performance.)
Arms of the long-recoil design are the familiar “Hump Back”
Browning auto-loading shotgun and other similar shotguns
made by Remington, Savage, and Breda and Franchi of Italy.
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FIGURE 70—Shown is an exploded view of a rifle at the moment of firing. The spring within the plunger tubedrives the hammer forward, thus driving the firing pin into the primer. The action is still locked. The bullet is stillin the barrel and gas behind the bullet is entering the gas vent port where it will activate the piston.
FIGURE 71—The bolt has been unlocked and driven back by the operating rod. The spring-loaded ejector pivots thefired case out of the rifle. The hammer has been forced back and cocked and a new cartridge rises into position for chambering. The bolt assembly, rebounding forward against spring tension, will strip off and chamber the nextcartridge.
Rifles 111
The Short-recoil design. Short-recoil designed firearms
also incorporate the breech bolt locked-to-barrel system of
the long-recoil design, in which the bolt and barrel recoil
together when the gun fires, thus compressing a recoil
spring. However, the barrel stops moving after only a short
distance (1/4 to 3/8 inch) and unlocks from the breech block.
Gas pressure and inertia then carry the breech block fully to
the rear until stopped by a buffer spring. The breech block
rebounds forward, picks up and chambers the next cartridge,
and is ready for firing.
The short-recoil system is usually used in handguns (the
famous Colt .45 M1911 is a prime example), but it was also
employed in the Johnson semiautomatic rifle of World War II
and in the comparatively recent Browning double-automatic
shotgun.
Blowback Design
In the blowback design, the barrel remains stationary while
the bolt or breech block moves to the rear under the impetus
of push from the exploding cartridge. There’s no connection
or linkage between the barrel and breech block. Timing is
dependent upon gas pressure, weight of the breech block,
and/or springs designed to hold the breech block in place
against the cartridge. Thus, blowback-operated systems
function through manipulation of the laws of inertia.
Arms that utilize the blowback design are usually low powered,
requiring a relatively short breech block movement. The only
centerfire rifles of blowback operation that come to mind are
Winchester’s semiautomatic .351 and .401-caliber models,
which many police departments use.
The Thompson submachine gun, and in fact most subma-
chine guns, are simple blowback-design weapons in which a
massive chunk of metal is used as a breech bolt that’s driven
rearward by the force of the burning gases. Since the breech
bolt is quite large, substantial inertia (the tendency of a body
at rest to remain at rest) must be overcome. By the time
the bolt starts to move to the rear and allow gas to escape,
the bullet is already out of the barrel. Moving forward, the
bolt cocks the action, then picks up and chambers a fresh
cartridge.
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Some blowback semiautomatics, when incorrectly assembled
or with badly worn parts, can fire fully automatic, constituting
dangerous and highly illegal firearms. Most, however, incor-
porate a “disconnector” that holds the hammer back and
prevents it from following the bolt to firing position, thus
making a separate trigger pull necessary for each shot.
Most .22 rifles in semiautomatic design are blowback-operated,
as are most low- to medium-powered handguns. We haven’t
found this system practical for high-powered rifles since the
comparatively large breech bolt required would result in an
unbelievably cumbersome, unwieldy, and heavy rifle. It has
been calculated that a .30/06 of blowback design would
require a breech block weighing about 27 pounds!
Note: Locking and unlocking in the usual sense is omitted in
most blowback designs.
Sequence of the Eight Functions inAutoloading RiflesFor purposes of explanation, we’ll discuss the popular
Remington 742 semiautomatic rifle. Its operation is typical of
all gas-operated semiautomatics, whether of short- or long-
stroke design.
1. As the shooter pulls the trigger, the sear disengages from
the hammer notch, permitting the hammer to rap the
firing pin, which then strikes the cartridge primer,
(1) FIRING the gun. Following passage of the bullet over
the gas port midway down the barrel, expanding gases
are metered through the port and downward into the
gas or impulse chamber.
2. This gas pressure acts against a small piston, which
forces the action bar and bolt assembly to the rear,
thus compressing the action spring. As it starts moving,
the bolt (2) UNLOCKS and the cartridge case is
(3) EXTRACTED from the chamber. Moving backward,
the bolt compresses the hammer spring, accomplishing
(4) COCKING. As the bolt stops, the ejector pin tips the
case from the action, thus (5) EJECTING the fired car-
tridge. This clears the path for the next cartridge, which,
under pressure of the magazine spring, has risen into
(6) FEEDING position.
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Rifles 113
3. The compressed recoil spring now forces the bolt
forward. It strips the in-position cartridge from the
magazine and forces it into the chamber, thus
(7) CHAMBERING. As the bolt closes firmly, the
lugs rotate, (8) LOCKING. The sequence repeats
automatically following each manual trigger let-off.
Winchester’s semiautomatic sporter, the Model 100, has a
unique self-metering gas system (within the cylinder) that
incorporates a cup-shaped piston facing the muzzle of the
rifle. This cup has a small hole that matches up with the
vent hole in the barrel. After sufficient expanding gases have
entered the two matching holes to operate the action, the
piston cup moves to the rear and cuts off the gas supply.
This self-metering device eliminates “pounding” and makes
for a smoother operating action.
The new Browning semiautomatic sporting rifle, first market-
ed in 1967, has an operating mechanism very similar to that
of the M1 carbine, in which a short-stroke piston operates
the action system.
By way of contrast, the M1 Garand takes its gas from a port
very close to the muzzle. It was originally thought that the
lessened gas pressure at that point would exert a longer,
slower push against the piston and minimize “slamming.”
A long operating rod was required, which caused other
problems and now doesn’t exist in more recent designs.
Troubleshooting Semiautomatic RiflesAn even greater variety of semiautomatic rifles is available
than bolt-action rifles. The Remington M 742 and newer
Models Four and 7400, the Browning BAR, and assorted mil-
itary-style rifles are gaining in popularity every day.
Caution: You should have a reference manual for any semi-
automatic rifle you work on. Obviously, it’s helpful to have a
reference manual available when working on any firearm, but
most especially when working on the three semiautomatics
listed above. They offer many chances for making mistakes,
which can cause serious trouble (Figure 72).
An acquaintance in Williamsport, MD, told me the following
story. My friend was experiencing difficulty opening a Franchi
M 500 12 gauge, five-shot automatic after firing it, so he
pried the bolt back with a screwdriver and unloaded the gun.
Then he worked the action. It seemed to free up and work
just fine, so he and his friends decided to continue their
rabbit hunt. First, he filled the magazine; then, he dropped
a loaded shell into the chamber and pressed the bolt release
button. A roar he described as “one long bang” tore the gun
from his hands and thrashed it against his face.
The gun had emptied the magazine so fast it sounded like
one explosion. The firing pin was stuck forward and the gun
fired, like most machine guns, from an open bolt. He said
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FIGURE 72—Exploded View of a Semiautomatic Action Rifle
Rifles 115
that anyone standing to his right would have been killed as
the gun spun to the right.
The story is something to think about at the very least. It
reminds me that a malfunctioning semiautomatic can be
a deadly machine. This is good reason to be extra careful
when working on the semiautomatics.
Crud
Again, crud causes the most problems. Crud is even worse
in semiautomatics because the gas pistons must be clean
and free of corrosion for the guns to operate well.
Broken Extractors
Besides crud, probably the worst offenders are worn or broken
extractors. Replacing broken extractors in the rifles we’re
discussing is no real problem.
Stuck Cartridges
The real problem comes when the head comes off a case and
leaves part of the case in the chamber. This precludes tap-
ping it out from the muzzle with a cleaning rod, as it’s diffi-
cult to get into the breech without complete disassembly of
the rifle. What should you do? Possibly, you could screw a
suitable size thread-cutting tap with a long “lead” or tapered
portion on the nose into the remaining brass. This would
furnish a shoulder against which you could drive a ramrod
to move the remaining portion of the case in the chamber.
Use a telescope gage to determine the inside diameter of
the remaining portion of the brass case and select the proper
size tap. It may be necessary to slightly grind the tap.
However, you should be able to get four turns on a fine
(NF) tap. Use a small ratchet wrench to turn the tap.
Note: Be careful not to turn the tap so far as to cut through
the brass and damage the chamber wall. When the tap is
in far enough for a good bite, put the ramrod through from
the muzzle and drive the stuck case out by driving against
the tap.
Rough Chamber Walls
One of the primary reasons for stuck cases is rough chamber
walls. You can polish the chamber walls by using a hacksaw
to slit about three inches of a short section of hickory ramrod
and folding a piece of garnet cloth so the cutting side is out.
Insert the Garnet cloth in the slit in the wooden ramrod
section.
Note: You can do the work from the muzzle end if you use a
long enough section of ramrod, but I prefer to disassemble
the rifle and do it from the breech end.
You fasten the ramrod in the chuck of a hand drill, which
you use to spin the rod with polishing cloth in the chamber.
If the chamber is very rough, you may wish to start with
coarser polishing cloth and finish with the garnet cloth. Such
a polishing will make extraction much easier and eliminate
most extraction problems.
Clip Feeding
Sometimes feeding cases from clips cause difficulty in rifles
like the Winchester M 77. Close up the front lips of the clip
if the loaded cartridge is hitting too high above the chamber.
If it is striking below the chamber, you can open the clip up
a bit to allow the case to hit higher. Often, polishing the feed-
ing ramp on self loaders will improve ammo feeding.
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Self-Check 7
Fill in the blanks in the following statements.
1. The Remington _______ is the only slide-action rifle to handle such high-intensity cartridges as the .30/06, .270, .308., etc.
2. The first really successful bolt-action design was the 11mm Mauser single-shot of 1871,which employed a true _______ design.
3. There are three basic groups of semiautomatic designs: _______ , _______ , and _______.
4. The difference between an auto-loading firearm and other designs is that of the eightfunctions, only one is performed manually and that is _______.
5. The Remington 760, essentially a Mauser turning-bolt design, has a _______ lockup.
Check your answers with those on page 130.
DOUBLE RIFLES
You won’t see too many double rifles (double-barrel rifles).
Although not common in this country, a surprising number
of these old-timers do turn up for needed repairs and adjust-
ments. The true double rifle looks much like a side-by-side
shotgun. It’s usually based on the same hinged breech
design (but beefed up) and has a shotgun-type extractor.
There the similarity ends.
A double rifle is actually two rifles in one, with separate
triggers and locks. If one malfunctions, the other can still
work. Don’t confuse double rifles with the European Drilling,
essentially a side-by-side double shotgun with a single slen-
der rifle barrel mounted under the tubes.
The double rifle is essentially a British specialty and has
never been popular in the United States. Only a small num-
ber were ever built in the United States. There was never a
real need for double rifles and the big drawback was their
high production costs (Figure 73). The twin rifle bores had
to be adjusted until shots from both barrels converged at the
same point—usually 50 to 100 yards. Adjusting the barrels
took many painstaking hours and frequently days by a master
armorer soldering, firing, resoldering ad infinitum. Most dou-
ble rifles were designed to stop a charging elephant. When
the time came to use the rifle for such a purpose, accuracy
had to be good—superior to the “accuracy” provided by double-
barrel shotguns with slugs printing perhaps a foot apart at
50 yards.
It would be impossible to manufacture double rifles today at
a price that would bring enough sales to warrant production.
Double-barreled rifles were, however, fairly common in the
black powder era for a brief time. None of the manufacturers
of double rifles stayed in business more than a few years.
The L. C. Smith Company, makers of a fine double shotgun,
also manufactured double-barrel rifles for a short time in
limited quantity. Winchester made at least one Model 21 in a
double rifle configuration, but such a firearm has never really
caught on in the United States.
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Most double rifles have traditionally been made in England,
Belgium, Germany, and Austria, where a few are still being
manufactured, primarily for hunters pursuing large, heavy,
dangerous game in Africa or India. Even though the double
rifle’s price is astronomical, the waiting list to purchase it is
long, with delivery scheduled from six months to as long as
two years.
Double rifles have always received the utmost attention,
respect, and care in areas such as Africa, where hunters of
elephant, rhino, Cape buffalo, and lion used them for many
years. Around the turn of the century, the bolt-action
repeaters of the time couldn’t use the exceedingly long, pow-
erful “African” cartridges. Therefore, heavy .40 to .60 caliber
double rifles, were introduced. No repeating rifles could (or
can) deliver a second shot faster and with less possibility of
malfunction. These double rifles were chambered for many
different types of cartridges, including the long-defunct black
powder types. Many were made with Damascus barrels, suit-
able for black powder loads only. You should treat any such
firearm coming into your gun shop for repair with great
respect. Almost without exception, double rifles are valuable
as functioning firearms or as collector’s pieces (which, indeed,
most are).
FIGURE 73—Fine double rifles are usually lavishly checkered and engraved, sometimes costing more than $5,000.
Rifles
Troubleshooting Double-barrel Rifles
Troubleshooting technique for double-barrel rifles is the
same as for double-barrel shotguns. Double-barrel rifles have
the same function and parts, such as the standing breech,
water table, pivot pin, and lock types, which are identical in
both. The only difference is that the rifles are heavier and
stronger in order to withstand the much higher pressure
loadings.
As already mentioned, regulation of the barrels is critical. If
two barrels aren’t shooting to the same point, it’s necessary
to heat them enough to soften the solder, move them a bit,
and resolder. A heavy steel frame known as a regulating
mount holds the barrels with clamps during resoldering.
Note: The study unit Shotguns gives more troubleshooting
details.
Single-shot Actions
Few rifle enthusiasts today give more than a passing thought
to how significantly the “lowly” single-shot breech-loading
rifle influenced and changed the course of history.
In the 1850s through the 1870s, the “new” breechloaders,
with their comparatively rapid reloading capability, provided
military supremacy for many armies that faced (and defeated)
other armies equipped with slow-firing muzzleloaders.
Hunters swept clean the North American prairies of buffalo
with powerful, long-range, single-shot Sharps and Remington
rolling-block rifles, some equipped with primitive, yet effec-
tive, telescopic sights.
The Dropping (or Falling) Block Design
The direct ancestor of most modern single-shots was the
Sharps rifle developed by Christian Sharps during the 1840s,
when percussion ignition largely replaced flintlocks. The
Sharps rifle was to single-shots what the Mauser was to
bolt-actions. Sharps’ dropping-block design, in which the
breech block rose and dropped vertically in mortises milled
in the receiver walls, was exceptionally strong and provided
120
Rifles 121
a perfect gas seal. Thousands of Sharps rifles were success-
fully converted to metallic rimfire and centerfire cartridges.
The Sharps rifles were originally designed for breechloading
of paper bags containing powder and projectile, which were
sheared at the tail by the rising block, thus exposing powder.
The original Sharps exposed-hammer design gave way to a
number of hammerless (concealed in frame) variations,
including the Sharps-Borchardt of 1870, the match-winning
American Ballards, the British Farquharson, and the famous
Stevens “Ideals.”
Probably the best-known Sharps progeny was the Winchester
single-shot of 1879, one of John Browning’s first designs sold
to Winchester (Figure 74). It was made in many different
forms for different cartridges, with the various designs known
as high-wall, low-wall, thick-wall, and thin-wall (referring to
receiver dimensions, of course).
Basically Lever-action Single-shots
All Sharps-inspired or derived designs were essentially single-
shot, lever-action rifles in that a pivoting trigger guard or
lever behind the guard operated the action. Moving the lever
forward dropped the breech block and exposed the chamber
for loading the cartridge. After firing, extraction (and some-
times ejection) occurred by opening and/or “snapping” the
lever (Figure 75).
Today, perhaps because of the nostalgia craze, single-shots
are again in big demand from hunters and shooters wanting
to “relive” the past and/or give game a better break.
FIGURE 74—Shown is Winchester’s world-famous dropping-block single-shot designed by John Moses Browning.
Modern centerfire one-at-a-timers include the Ruger No. 1,
similar in appearance to the handsome and venerable British
Farquharson, but greatly improved mechanically; and the
Browning single-shot, basically a modified Winchester Hi-Wall.
Rolling-block Design
Like the Peabody action, best known as the Martini, the
Rider rolling-block system was invented by one man, Leonard
Gieger. It then became famous through the modifications of
another, Joseph Ryder, or Rider (Figures 76 and 77). Both
men had patents on a similar rolling-block design, but
Gieger’s was the true basis of the Remington rolling block
(Figure 78). Ryder, employed by Remington, slightly changed
Gieger’s design for production (Remington had purchased
both patents).
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FIGURE 75—Two Modern Single-shot Rifles. Top: New Browning, Bottom: Ruger No. 1.
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The rolling-block design is the simplest of all single-shots
(Figure 79). The design is enormously strong and consists
basically of two pivoting breech-locking mechanisms, one
mounted behind the other. The mechanisms are attached
to the frame by large axis pins.
The primary mechanism is the breech block, pierced and
containing the firing pin. When the shooter cocks the hammer
back, the firing pin can be rolled up (and down) from the
chamber by means of a thumb spur or extension. When flush
against the chamber, the breech block is spring supported,
but not locked into place.
The second mechanism is the hammer, mounted behind
the breech block, also by an axis pin. When the hammer
is cocked back and the breech block is rolled up against
FIGURE 76—Here’s the Peabody tipping-blockmechanism showing the principle of operation.
FIGURE 77—Shown is the Martini-Henrymechanism illustrating the variation andimprovement of the basic Peabody design.
FIGURE 78—Replica Rolling-block Baby Carbine by Navy Arms
FIGURE 79—Cutaway View ofthe Remington Rolling-blockSystem Showing the Breech-locking Mechanism at Momentof Firing
the chamber (two separate operations), the rifle is ready to
fire. Release of the trigger lets the hammer fall. However,
before the hammer can strike the firing pin, a projection
under the surface of the hammer assembly slides smoothly
into place behind and under the breech block. This locks the
breech bolt firmly against the chamber, a split second before
the hammer hits the firing pin.
The Remington rolling block wasn’t perfected until just after
the Civil War and the United States Army never adopted it.
However, the U.S. Navy ordered 12,000 rifles in 1867. Also,
more than one million RB military rifles and carbines in
7mm (7 � 57), .45/70, and other calibers were sold to
Denmark, Sweden, Norway, Spain, Egypt, Argentina, China,
and other countries, primarily between 1867 and 1879. Its
popularity was short-lived, however, as the first bolt-action
Mauser was just over the horizon, appearing in 1881.
In the 1950s, the United States imported “surplus”
Remington rolling blocks by the tens of thousands, with
prime specimens selling for as little as $9.95. One intrepid
West Coast importer advertised them “complete with plans
for making a rolling-block rifle Moor lamp,” for $7.95. Today
replicas made by Navy Arms are selling very well at $150
U.S. dollars!
While seldom used for sporter conversions, authentic rolling-
blocks are fast becoming collector’s items.
The Sequence of the Eight Functions inSingle-shot Rifles
If you were to hold an empty Ruger No. 1 single-shot rifle
in your left forehand, push down on the lever release, which
is spring-loaded and located immediately behind the trigger
guard, and then push the lever down and forward, you would
accomplish the following.
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Rifles 125
The gun is (1) COCKED as the striker mechanism pushes
back against the spring tension of the mainspring until the
sear catches and holds the striker. While being cocked, the
action is also being (2) UNLOCKED as the breech block
drops, exposing the chamber for feeding and loading. Here,
(3) FEEDING is by hand, and the cartridge is usually
(4) CHAMBERED manually. As the lever is brought back up,
the block rises behind the cartridge, thus (5) LOCKING the
action. The rifle is now ready to fire. After (6) FIRING, the
lever is moved down and forward, dropping the breech block
in its mortise and, depending upon how the user has set the
ejector/extractor mechanism, the cartridge is (7) EXTRACTED
and (8) EJECTED from the gun. Actually, after the shell is
extracted about 1/4 inch, the ejector kicks it from the gun.
Troubleshooting Single-shot Rifles
Procedures for troubleshooting single-shot actions depend
on the type of action involved. The single-shot classification
includes representatives of every type action. Also, you’ll find
some actions, such as the falling-block, only in single-shot
rifles.
Action types include bolt, lever, tip up, falling block, rolling
block, side break, and trapdoor to name some of the most
common. Where applicable, consult troubleshooting instruc-
tions already provided for an action type. Further information
specific to certain action types follows (Figure 80).
Trapdoor Rifles
The trapdoor rifle operates from a section of breech, which is
hinged like a trapdoor that lifts up and is locked by a latch
at the rear. The action is a very weak. The only ones made
were the Springfield army rifles, which were chambered for
the .45-70, .45-90, and .50-70. There are many trapdoor
rifles around, although they have appreciated so much in
value as collectors’ items that very few people will take them
into the woods to hunt with them. I killed my first deer with
a Springfield trapdoor rifle chambered for .45-70 using a 405
grain bullet at around 1,200 fps. It’s important that only
loads listed for the trapdoor rifles be fired in them. There are
loads for the Marlin .45-70 rifles that will completely wreck
a trapdoor model and likely severely injure the person who
fires the load. These were black powder rifles and won’t
handle smokeless powder pressures.
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FIGURE 80—Exploded View of a Single-shot Action Rifle
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The critical maintenance is to make sure the dog latch is
seating all the way down and that the hinge pin at the front
of the trap is in good condition.
Falling-block Designs
Falling-block rifles work on the same principle as a breech
block, which cams into position at the rear of the bore. They
also operate on the Sharps’ principle in which a breech block
slides up and down in a box space as a lever below the breech
operates it. The lever also usually acts as the trigger guard.
The only maintenance is to keep the breech greased where
the block slides. Also, keep the hinge pins well oiled and in
good condition.
The Tipping-block Design
The tip-up action is just like a single-shot, top-break shot-
gun. The barrel tilts down from a hinge in front of the water
table, and the firing pin is inside the standing breech.
Maintenance is the same as a tip-up shotgun.
The Side-break Design
The side-break action is like a tip-up except that the barrel
moves to the side to clear the standing breech and allow
loading and extraction. Stevens made the side-break for a
short time.
The Rolling-block Design
Maintenance of the rolling block is easy as it has only four
moving parts. You must keep the heavy breech block and
hammer screws/axles well oiled. The extractor seems to wear
fast. You can easily make the extractor from scrap metal in a
couple of hours. Other than occasional firing pin replacement,
this is about all the maintenance required to keep a rolling
block rolling.
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Self-Check 8
Indicate whether the following statements are True or False.
_____1. The prairies of North America were swept clean of buffalo with powerful, long-range,single-shot Sharps and Remington rolling-block rifles—some equipped with primitive,yet effective, telescopic sights.
_____2. Maintenance of the rolling block is easy, with only eight moving parts.
_____3. The rolling-block design is the most complicated of all single-shot rifles.
_____4. Probably the best known Sharps progeny was the Winchester single-shot of 1879,one of John Browning’s first designs sold to Winchester.
_____5. Troubleshooting technique for double-barrel rifles is the same as for double-barrelshotguns.
Check your answers with those on page 130.
129
Self-Check 1
1. False. The Jaeger was short barreled and had a short,
heavy stock.
2. False. The wheel-lock allowed for better accuracy.
3. True
4. False. A caliber is .01 inch.
5. True
Self-Check 2
1. never
2. accuracy
3. abrasions
4. pivot point
5. gas cutting
Self-Check 3
1. True
2. True
3. False. You can use longer barrels.
4. True
5. False. A barrel’s weight, diameter, and stiffness are all
important to a rifle’s accuracy.
Self-Check 4
1. True
2. False. Stainless steel isn’t rustproof.
3. False. The extrusion process weakens the steel.
4. True
5. False. Barrel straightening is accomplished by placing
the barrel across two heavy steel fingers and applying
pressure to it between the support points.
An
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Self-Check Answers130
Self-Check 5
1. Creep
2. half-cock
3. liability
4. aftermarket
5. case hardened
Self-Check 6
1. True
2. True
3. True
4. False. The lockup is like the multilug bolt-actions.
5. True
Self-Check 7
1. 760 “Gamemaster”
2. turning-bolt
3. gas-operated, recoil-operated, blowback
4. firing
5. multiple-lug
Self-Check 8
1. True
2. False. It has only four moving parts.
3. False. The rolling-block design is the simplest of all single-
shot rifles.
4. True
5. True
Examination 131
925 Oak Street
Scranton, Pennsylvania 18515-0001
Rifles
When you feel confident that you have mastered the material in this study unit, complete the following examination. Then submitonly your answers to the school for grading, using one of the exami-nation answer options described in your “Test Materials” envelope.Send your answers for this examination as soon as you complete it.Do not wait until another examination is ready.
Questions 1–20: Select the one best answer to each question.
1. The primary advantage of the multiple locking lug design overthe single locking lug is
A. shorter bolt lift.B. decreases in bolt handle and scope bell clearance.C. an increase in bolt locking strength.D. faster repeat shots.
2. How many times in 50 yards should a bullet spin when fired froma barrel that has a 1 inch in 12 inches rifling twist?
A. 50 C. 150B. 62 D. 600
3. You can greatly lessen bore erosion by using
A. lighter-than-maximum loads.B. reloads.C. heavy loads to clean out the barrel.D. new brass only.
EXAMINATION NUMBER:
02530501Whichever method you use in submitting your exam
answers to the school, you must use the number above.
For the quickest test results, go to http://www.takeexamsonline.com
Ex
am
ina
tion
Ex
am
ina
tion
Examination132
4. What rifle had the first ignition system that was dependable in bad weather?
A. Jaeger C. SnaphaunceB. Matchlock D. Caplock
5. The rear diameter of a barrel is generally determined by the
A. caliber. C. type of barrel.B. size of action. D. barrel length.
6. The shock waves along the length of the barrel are called
A. rifling. C. bullet yaw.B. nodes of vibration. D. the Coriolis effect.
7. The actual weight of a barrel is determined by the caliber (bore diameter) and the
A. cartridge size. C. outside diameter.B. bullet weight. D. type of metal finish used.
8. You should lap a barrel to
A. make the bore smaller. C. restore accuracy.B. make the rifle shoot harder. D. reduce rifling.
9. Gas ports are engineered into the modern rifle to
A. reduce chamber pressure. C. increase velocity.B. reduce recoil. D. protect the shooter.
10. The most popular barrel length of centerfire rifles is
A. 20 inches. C. 28 inches.B. 24 inches. D. 30 inches.
11. The famous Kentucky Rifle was actually the
A. Massachusetts Rifle. C. Virginia Rifle.B. Pennsylvania Rifle. D. Mississippi Rifle.
12. The first rifled barrels were probably made in
A. England. C. France.B. Italy. D. Germany.
13. The optimum method for preventing burrs inside the bore when machining recoil compen-sating ports into the barrel is to use
A. a hack saw. C. an electric discharge machine.B. a drill press. D. a rat tail file.
Examination 133
14. _______ steel is the type used in most gun barrels intended for use with today’s high-powercartridges.
A. Ordnance C. NickelB. Stainless D. Gun barrel grade
15. A good pull weight for triggers on hunting rifles is in the
A. 10 to 15 ounce range. C. 50 to 75 ounce range.B. 25 to 40 ounce range. D. 80 to 100 ounce range.
16. A floated barrel is one that
A. rests on the stock only at the forend tip and receiver ring.B. is fully bedded for the entire length of the stock.C. doesn’t touch the stock forward of the receiver ring.D. won’t experience nodes of vibration.
17. You can best counter gas cutting in barrels by
A. using undersized bullets.B. using black powder.C. using properly sized, well-made bullets.D. using lead bullets.
18. The first gun barrels were probably made of
A. stone. C. iron.B. bamboo. D. copper.
19. Bullet yaw is the term used to describe a bullet’s
A. velocity.B. disintegration ratio.C. travel in a spiral course around its true bullet path.D. impact power.
20. A .40 caliber muzzle-loading rifle has a land diameter of
A. .004 inch. C. .100 inch.B. .040 inch. D. .400 inch.