BALLISTICSBullets and Casings

TIMELINE OF BALLISTICS EXAMINATION

1923: FBI Bureau of Forensic Ballistics established

1929: weapons used in the St. Valentine’s Day massacre identified by matching bullets

1992: Drugfire database is established 1996: NIBIS is established by the ATF 2000: NIBIN is established by merging of

Drugfire and NIBIS

TYPES OF BULLETS

Full Metal Jacket: projectile in which the bullet jacket encloses the entire bullet, with the usual exception of the base; most common use of this ammunition is target shooting

TYPES OF BULLETS (CONT.)

Jacketed Soft Point: bullet designed with the soft lead core exposed at the nose; typically used for hunting; usually have Cannelure--groove around a bullet or cartridge case; Typically found on revolver and rifle bullets

TYPES OF BULLETS (CONT.)

Jacketed Hollow Point: bullet designed with a jacket, typically copper, surrounding the lower portion; the nose of the bullet has a hollow point; allow for easier expansion or “mushrooming” upon contact with an object; this increases the surface area of the bullet

TYPES OF BULLETS (CONT.)

Lead Round Nose: elongated projectile made of a lead alloy with a rounded nose; typically used for target shooting

TYPES OF BULLETS (CONT.)

Semi-wadcutter: bullet designed with a truncated nose and sharp shoulder; used for target shooting, the sharp shoulder on the bullet produces a clean round hole in paper

TYPES OF BULLETS (CONT.)

Wadcutter: cylindrical bullet with a sharp shouldered nose intended to cut target paper cleanly to facilitate easy and accurate scoring

TYPES OF BULLETS (CONT.)

Boat Tail: bullet having a tapered or a truncated conical base; the tapered cone provides increased stability throughout it’s flight

TEST-FIRE

Weapon is fired into a water tank or gel block This captures the bullet without damaging it The test-fire bullet can be compared to

markings on the suspect bullets

CLASS CHARACTERISTICS All class characteristics

are measurableCaliberNumber of lands and

groovesWidth of the lands and

groovesDirection of twist

1 2 3

MARKS ON CARTRIDGES

Firing Pin Marks: made on the bottom of the cartridge by the firing

pin as it strikes the bottom of the cartridge when the firearm is shot

usually appears on the center of the cartridge

MARKS ON CARTRIDGES (CONT.)

Breechblock Marks: during the shot, the explosive force pushes the

bullet forward and at the same time, an equal and opposite force pushes the cartridge casing backward against the breechblock, leaving marks on the casing

the breechblock prevents the cartridge from shooting toward the user as it recoils

marks appear as parallel lines, circular lines, or stippled pattern

MARKS ON CARTRIDGES (CONT.)

Firing Pin Mark Green arrows are pointing to parallel breechblock marks

MARKS ON CARTRIDGES (CONT.)

Extractor and Ejector Marks: Minute scratches produced as the cartridge is

placed in the firing chamber are extractor marks

Scratches produced as the cartridge is removed from the chamber after firing are ejector marks

Extractor and ejector marks are produced only in semi- and fully automatic weapons

DATABASES

National Integrated Bullet Identification System (NIBIS): ATF database that has computer files of ballistic markings of firearms used in previous crimes

Drugfire: FBI database that focuses on cartridge casings

These two databases were merged to form the National Integrated Ballistics Information Network (NIBIN)