BALLISTICS - PowerPoint Presentation

Slide1

BALLISTICS

Bullets and CasingsSlide2

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 NIBISSlide3

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 shootingSlide4

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 bulletsSlide5

Types of bullets (cont.)

Jacketed Hollow Point:

b

ullet

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 bulletSlide6

Types of bullets (cont.)

Lead

Round

Nose:

elongated

projectile made of a lead alloy with a rounded nose; typically used for target shooting Slide7

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 paperSlide8

Types of bullets (cont.)

W

adcutter

:

cylindrical bullet

with a sharp shouldered nose intended to cut target paper cleanly to facilitate easy and accurate scoringSlide9

Types of bullets (cont.)

Boat Tail:

bullet

having a tapered or a truncated conical

base; the tapered

cone provides increased stability throughout it’s flightSlide10

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 bulletsSlide11

Class Characteristics

All class characteristics are measurable

Caliber

Number of lands and grooves

Width of the

lands and grooves

Direction of twist

1

2

3Slide12

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 cartridgeSlide13

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 recoilsmarks appear as parallel lines, circular lines, or stippled patternSlide14

Marks on Cartridges (cont.)

Firing Pin Mark

Green arrows are

p

ointing to parallel

b

reechblock marksSlide15

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 marksExtractor and ejector marks are produced only in semi- and fully automatic weaponsSlide16

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