The Small Arms Review • Vol. 10 No. 8 • May, 2007 SAR Hydra Artic… · upper receiver conversion is complete. The Lower Receiver Most people would agree that the weak-est link

The Small Arms Review • Vol. 10 No. 8 • May, 2007

Visit the SAR website at: www.smallarmsreview.com

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There is an abundance of caliber con-versions, barrel lengths and configurationoptions available for the firearm that hasbeen the primary service weapon of theUnited States military for over 40 years.In order to make such radical changes to asingle rifle, it has been necessary to pro-cure a new, barreled upper receiver, amatching rail system, and specialty maga-zines with proprietary adapters. At leastthat used to be the case - until now. Enterthe Hydra Modular Weapons System fromMGI.

Imagine having one firearm, in this casea registered M16, and having the abilityto fire numerous calibers. That is not sucha big stretch since several conversions in

Very few firearms can claim to be as versatile as the AR-15/M16. Thanks to MGI thespectrum just widened even more - much more.

the form of barreled upper receivers havebeen available for a number of years. Whatif you could make the caliber change inless than 2 minutes without using anytools? Again, nothing very spectacularbecause changing the barreled upper re-ceiver and bolt is a fast and easy process.What if you could do this and continueusing your upper receiver and rail system

without even having to disassemble thefirearm? Now that is something radicallydifferent.

In the Beginning

The Hydra Modular Weapons System isa combination of AR-15/M16/M4 up-grades going back for decades. Mack

Right: In order to change the maga-zine-well all the operator needs to dois (A) depress the trigger guard de-tent and swing the guard down. (B)Depress the magazine release buttonand lift the magazine-well up and offthe receiver. (C) Place the new maga-zine-well down on the receiver, align-ing the dovetail slots until it snaps andlocks onto the magazine release. (D)Replace the trigger guard.

A B

C D



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Gwinn Jr., President of MGI holds over25 firearms related patents. The originalfounder of several firearms related com-panies including Bushmaster Firearms andMWG, Gwinn has been involved in thefirearms industry for almost 4 decades.While many of his designs are unrelatedto the AR-15/M16/M4, such as the M2HB-QCB, his latest venture, MGI certainlyfocuses on this weapons system and boasts

impressive upgrades and radical designchanges.

The Upper Receiver

As reviewed in Small Arms Review (Vol.8, No. 3, December 2004) the MGI QuickChange Barrel (QCB) Upper Receiver al-lows the shooter the ability to quicklychange barrels with no tools in less than a

minute. The QCB Upper Receiver hasundergone several upgrades and modifi-cations in the last two and a half years, in-cluding a complete rail system as the stan-dard handguard. The MGI QCB-Chandguard utilizes four 5.75-inch M1913Picatinny rails, each at 3 o’clock, 6o’clock, 9 o’clock and 12 o’clock. The12 o’clock (top) rail is completely regu-lated with the flattop rail on the upper re-ceiver giving the operator several sight andaccessory options. They are manufacturedso precise that the upper and handguardcan even be “bridged” creating a top railover 13 inches in length when used with acarbine length barrel and gas system. Forthose who wish to use a full-length barreland gas system, MGI also offers a 5.5-inchhandguard/rail extension. When utilizingthis extension the top rail is almost 19inches in length.

Another major upgrade to the new MGIQCB-C Upper Receiver is the addition ofthe barrel locking arm retaining block.This retaining block slides on the 6 o’clockPicatinny rail and slides over the barrellocking arms, holding them firmly andeliminating anything sticking out that couldbe caught on clothing or foliage.

Like the original QCB Upper Receiverthe new QCB-C variation still uses factoryAR-15/M16/M4 barrels. There is nothingproprietary that needs to be purchased touse this system. If you have a factory bar-rel you wish to use with the QCB UpperReceiver, all you need to do is remove thedelta ring, the barrel nut, the sling swiveland the front handguard keeper and it isready to use. No special parts or accesso-

Below: In the red circles are two different 10-round groups of 5.56x45mm ammo, fired individually after completelyswapping calibers and firing two 5-round groups of 7.62x39mm ammo as shown in the blue circle. This target on the leftwas placed at 50 yards from the shooter and both groups were fired using the same point of aim. A second test wasconducted simultaneously at 100 yards and the results are visible on the target to the right.



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ries are necessary and all existing barrelswork fine. In the case of changing cali-bers as well as barrel lengths the correctbolt and bolt carrier are installed and theupper receiver conversion is complete.

The Lower Receiver

Most people would agree that the weak-est link in AR-15/M16/M4 caliber conver-sions is the feeding system. The shape,function and interior dimensions of theoriginal magazine-well don’t easily allowthe use of many other magazines. Whenothers are utilized, special and sometimesexpensive adapters are typically necessary,and at times, mandate the use of heavilycustomized proprietary magazines. Thesecan also be quite expensive since they arenot surplus or even “off the shelf” items.The performance with some of them hasalso been less than acceptable at times dueto the constraints of the original magazine-well dimensions. When there are prob-lems, magazine related feeding and func-tion issues always seem to lead to the ma-jority of the troubles. Anyone who hastried to push several 7.62x39mm roundsinto a standard 30-round AR-15 magazineand expect it to feed reliably when usedwith a 7.62x39 upper receiver has undoubt-edly faced the same problems. In this par-ticular situation, the larger diameter of the

rounds necessitatesmore curvature in thefeeding device in or-der to freely advanceand feed correctly.The straight shape ofa factory AR-15/M16/M4 magazine-welldoes not allow for thismagazine shape.

This major feedingproblem has been re-solved with the MGIHydra ModularWeapon System bysimply allowing theuser to utilize the cor-rect magazine for thecorrect caliber. Thisgives the proper pre-sentation of the car-tridge in both heightand feed angle, as itwas originally de-signed for, using fac-tory magazines.When shooting5.56x45 (.223 Rem),standard AR-15magazines are used.When converting to 7.62x39mm, standardAK47 magazines are used. When shoot-ing .45ACP, Grease Gun magazines areused and when using a 9x19mm system,Sten magazines (and soon Glock, Uzi andColt magazines) can be utilized. All thesemagazines work in their original, unmodi-fied condition, and all without the use of

expensive and troublesome magazine-welladapters.

This advancement in the MGI Hydrafeed system has been accomplished by de-signing the lower receiver to accept sev-eral magazine-wells, so the correct maga-zine can always be used with the correctcaliber, bolt and barrel. The magazine-well

Above: Due to the design of the Modu-lar Weapon System, it breaks downand fits in an extremely small pack-age. All the parts in this briefcase arelaid out in the photo below it.



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can be removed and replaced with no toolsand easily accomplished in under 1 minute.At the present time, magazine-wells areavailable in 5.56x45mm (.223 Rem) and7.62x39 with others in the final stages ofproduction including 9x19mm and 45ACP.Provisions for several other calibers arealso being developed including .22LR, .22Magnum, .40 S&W, 7.62x25mm and manymore.

The Complete Modular System

Even though the MGI QCB Upper Re-ceiver is completely compatible with allMil-Spec AR-15/M16/M4 lower receivers,and the MGI Modular Lower Receiver iscompatible with all Mil Spec upper receiv-ers, the real potential of their flexibilityhappens when they are used in conjunc-tion with each other. Several other com-

ponents have also been developed anddesigned to be used in this system andwhen combined, create entirely new pos-sibilities and options that never existed inthe past.

The Defender D-Ring

The addition of the MGI “Defender” D-Ring is standard in all complete weaponssystems. The D-Ring increases the reli-ability of the AR-15/M16/M4 by virtuallyeliminating extraction problems and in-creases typical extractor spring force by 4times over the factory spring. The D-Ringis used by several police departmentsacross the nation and is used extensivelyby members of the armed forces in the WarOn Terror. Many factors including gas porterosion can contribute to creating a higherrate of fire causing an extreme centrifugalforce on the extractor as the bolt rotatesand unlocks. This centrifugal force cancause the extractor to lift and can lead to adangerous failure to extract. The addi-tional force on the extractor keeps it closedin the position it was designed to be in,insuring a positive extraction. Sandy ordirty conditions can also lead to more dragon the casing after firing and this extraspring tension creates a more positive ex-traction in these cases as well. Over theyears, some end users have used commonO-rings from the local hardware store toreach the same goal as the D-Ring. Whilethey are inexpensive and plentiful they canlead to a malfunction due to inferior mate-rials compared to the D-Ring. Standardo-rings are not designed to take the harshand rapid repetitive compression that theD-Ring was engineered for. Also, whilethe shape of the D-Ring holds it in posi-tion, a standard o-ring can slip and causethe extractor to stick open.

The MGI Regulated Gas Tube

The MGI Regulated Gas Tube is anotherimportant system upgrade and greatly as-sists in solving gas port erosion problems.It is completely adjustable allowing theshooter to control the amount of gas usedto operate the system. The rifle can betweaked for particular ammunition or spe-cifically adjusted just for the current con-ditions it is operating in. It is installed justlike a standard gas tube and is adjusted witha standard Allen wrench.



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MGI Rate Reducing Buffer

The MGI Rate and Recoil ReducingBuffer assists in increasing hit probabilityby reducing felt recoil and reducing muzzlerise. These buffers were tested extensivelyin Small Arms Review (Vol. 7, No. 8, May2004) and performed extremely well. Thebuffer utilizes a mechanical operating sys-tem and is not sensitive to extreme tem-peratures like similar hydraulic systems.During all phases of testing, the MGI RateReducing Buffer dramatically reducedmuzzle rise and consistently lowered therate of fire when used with fully automaticfirearms. The reduction in rate of fire isdirectly related to the original cyclic rate:the faster the cyclic rate, the greater thereduction in rate of fire. Never did the rateof fire become slow enough where they didnot still fire with 100% reliability.

The 7.62x39mm upgrade

While 7.62x39mm conversions to theAR-15/M16/M4 are nothing new, MGI hasengineered several improvements to theirsystem. As mentioned previously, theModular Lower Receiver will accept amagazine-well that allows the use of stan-dard AK47 magazines. In order to func-tion properly with standard AK47 maga-zines, the bolt carrier has also been slightlymodified from the original design. Oncemodified, the carrier will still work finewhen used in conjunction with the5.56x45mm system so it is actually a multi-

Above: With a barrel in place, lock or hold the bolt to its rear-ward position and snap the retaining lock (A) up as illustrated.Slide the retaining block (B) to the front to expose the lockingarms. Swing the locking arms (C) open and the barrel will slideout to the front. To install the new barrel reverse the procedure.When sliding the retaining block over the closed locking arms(D) you will notice a small amount of pressure as the locking armsclose tightly during each change. This provides uniformity, nec-essary for accuracy and dependability that the MGI QCB is ableto provide. Snapping the retaining lock back down (E) completesthe barrel change procedure.

MGI QCB-CBarrel SwapProcedure

Left: Close-up view of the dovetail locking mechanism on the MGI lower receiver. Right: Close-up view of the dovetaillocking mechanism on the AR15 mag-well (left) and on the AK47 mag-well (right).



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use carrier. The MGI QCB-C upper re-ceiver has also been designed to acceptthese AK47 magazines as well as a multi-tude of others and has slightly different in-ternal dimensions than standard upper re-ceivers in order to facilitate this conver-sion.

One of the newest MGI innovations inthis caliber conversion is in the fire con-trol group. It is well known that the prop-erties of rifle primers are very differentdepending on the country of origin andtype of ammunition. Some Com-Bloc7.62x39mm primers can react quite differ-ently than NATO 5.56x45 primers and thisdifference has led to an unreliability fac-tor when utilized in some firearms. TheCom-Bloc firearms designed specificallyfor this caliber have addressed this in theirdesign and do not have the same reliabil-ity issues. After years of research and de-velopment MGI believes they have nowaddressed these differences and will soonbe offering a bolt and firing pin upgradespecifically designed for use with this cali-ber. The author has had the opportunity totest the bolt upgrade in its prototype form,and the results thus far have been excel-lent. Early tests have shown that when thisupgrade is utilized with otherwise unus-able ammunition, the failure to fire rate isalmost completely diminished. Althoughthis upgrade is designed to be used in con-junction with the MGI Modular WeaponsSystem, it will work with any 7.62x39mmAR-15/M16/M4 conversion to increasereliability.

Range Time

Numerous hours were spent at the rangewith all aspects of the MGI Hydra Modu-lar Weapons System. While several thou-sands of rounds have been fired in all con-

figurations, there are a few interestingpoints that need to be discussed.

One pressing question in particular (andrightly so) always follows a system de-signed with a quick-change barrel mecha-nism: “How well does it re-zero after re-moving and replacing the barrel?” A le-gitimate question and a series of tests wereperformed to find that answer when pre-production testing first started.

The tests we designed were far more in-

tense than simply shooting a group, removebarrel, reinstall barrel and re-shoot groupexercise. We were looking for and mea-suring point of impact shift, not snipergrade accuracy. Both barrels were already“well seasoned” from lots of rate of firetesting and we were running WolfPolyformance ammunition this day. Thiswas to be conducted as a real-world exer-cise, not a bench-rest rifle, solenoid-firedelectronic trigger test. Rounds would be

Below: The MGI receiver with an AR-15 mag-well installed on the left, and with an AK47 mag-well installed on the right.

Top: The handguard on the new MGI QCB-C Upper Receiver has 4 M1913Picatinny rails for use with numerous optic and accessory options.

Above, center: The MGI QCB-C handguard extension attaches to the standardQCB-C upper receiver allowing use of barrels with full-length gas systems.



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fired in a rapid-fire fashion, allowing asecond or two between each shot but with-out the luxury of any slow-fire deep breath-ing exercises like we are all taught to do inNRA Shooting School.

Targets were set at 50 yards and at 100yards. The rifle was setup in 5.56x45 witha 4x12x40mm scope and was bore-sighted.It was “zeroed” in 5.56x45mm on the 50-yard target. That would be the last of thescope adjustments for this exercise. At 50yards, ten rounds of 5.56x45mm were firedusing the “X” as the point of aim. Afterletting the barrel cool for just a few sec-onds the barrel, bolt and magazine-wellwere swapped out for the 7.62x39mm sys-tem. At that point 5 rounds of 7.62x39mmwere fired at the 50-yard target using thesame point of aim as before. Immediatelyafter firing the 7.62x39mm rounds the riflewas swapped back to 5.56x45mm and an-other 10 rounds of 5.56x45 were firedagain, with the original point of aim. Fin-ishing the 5.56x45, the rifle was convertedback to 7.62x39 where we immediatelyfired 5 more rounds.

We completed the exercise and repeatedit exactly the same at 100 yards. We werevery pleased with the outcome and sur-prised at how close the groups were, eventhough they were completely different bar-rels and very different calibers. We didn’tknow what to expect in accuracy as far asthe original barrel and ammo comboswould be concerned, and were extremelyimpressed when the original point of im-pact was re-established after multiplechanges. Some photos are included in thisarticle showing the results of these tests.It must be stressed again that these werenot accuracy tests, just redundant point ofimpact tests and the system scored verywell. If we used match grade (or even “not-shot-out”) barrels with proper trigger timeand discipline combined with match ammowe have no doubt the results would be evenmore dramatic. But that was not the pointof this exercise.

The Future

Even though the MGI Hydra ModularWeapon System holds some extremely

Right: An MGI Modular Lower Re-ceiver with AR-15 mag-well below aQCB-C upper receiver with the ex-tension installed for the 20-inch bar-rel above.

Right: - An MGI Rate Reduc-ing Buffer to the left of a fac-tory M16 buffer. The MGIBuffer consistently reduces feltrecoil, and increases hit prob-ability by lowering the cyclicrate and taming muzzle rise.

Below: A Defender D-Ring pic-tured below an M16 extractor.The D-Ring slides over the origi-nal extractor spring giving it ap-proximately 4 times the extrac-tion power.



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impressive design characteristics, theproject is still in its very early stages andis evolving faster than this writer can keepup. Some of the designs on the drawingboard must remain behind closed doors atthis time but other upgrades that have beencleared to mention include a belt-feedmechanism, an open bolt option for regis-tered full-auto users and even an open-bolt/closed-bolt system, something manythought could never be developed. Thenew open-bolt/closed-bolt system is in thefinal phases of testing and will be enteringthe pre-production phase very soon. Thisunique design allows the open-bolt func-tion when utilized in fully automatic andfires in a closed-bolt mode when switchedto semiautomatic. This design allows formaximum cooling and increased safetywhen shooting in fully automatic withoutcompromising accuracy when shooting insemiautomatic. This writer has had theopportunity to handle this upgrade in itsvarious stages and it is very exciting in-deed.

Several more calibers and magazine-well options are slowly making their waytowards the market. Some additions areas radical as 7.62x51NATO and .458SOCOM (all based on the same lower re-ceiver and upper receiver design) and someare simply additions to fit more commonmagazines allowing “duty” magazines tobe utilized helping to launch the MGI Hy-dra Modular Weapon System even higheras a convenient companion rifle for almost

any standard “duty” sidearm. To providean even more unique addition to the sys-tem, all pistol calibers are now being testedutilizing the standard gas system insteadof the traditional blowback style functionthat has become so common. In MGI pro-totype firearms, the early results show farless recoil and better controllability.

Conclusions

The MGI Hydra Modular Weapon Sys-tem is the most radical and versatile up-grade to the AR-15/M16/M4 that thiswriter has had the opportunity to handleto date. With numerous caliber changesavailable and several barrel lengths, allwhile using standard unmodified barrelswith absolutely no tools necessary forchanging, it is in a class of its own. Com-bined with the lower receiver that uses in-terchangeable magazine-wells allowingcommon, correct, unmodified magazineswith these caliber conversions, this systemis well ahead of its time in the standard

A factory barrel ready for use with an MGI QCB upper receiver. Fac-tory barrels are utilized with no modification other than removing thedelta ring, barrel nut, and front handguard keeper. This system givesthe operator a completely free-floating barrel system.

Black Rifle Market. We are looking for-ward to additional releases from MGI andwill be sure to keep the readers of SmallArms Review informed as they come to themarket.

Editors Note: Due to his involvement inthe firearms community, as well as withSmall Arms Review magazine, the authoris involved with several related businessesin the area of consulting, research & de-velopment and testing & evaluation. MGIis no exception to this, and due to theseunique relationships he is able to provideour readers with first look and premierearticle content on occasion.

MGIDept. SAR

102 Cottage StreetBangor, Maine 04401

Phone: (207) 945-5441Email: [email protected]: www.mgimilitary.com

Right: The MGI Regulated GasTube allows the shooter to determinethe optimum amount of gas to oper-ate the firearm with varying ammu-nition and shooting conditions.

Documents

The Small Arms Review • Vol. 10 No. 8 • May, 2007 SAR Hydra Artic… · upper receiver conversion is complete. The Lower Receiver Most people would agree that the weak-est link