Ballistics

cartridge

Ammunition used in modern rifles and handguns; a case containing primer, gunpowder, and a bullet

primer

ignites the gun powder

caliber/gauge

diameter of the gun barrel

firing pin, hammer

In order to fire the cartridge, the primer must first be ignited. To accomplish this a firing pin strikes the center ring of the cartridge.

grooves

the cut or low-lying portions between the lands in a rifled bore

Rifling

The spiral pattern of lands and grooves in the barrel of a firearm

lands

the raised portion between the grooves in a rifled bore

Striae/striation

1.Scratches on a fired bullet,

2.like a barcode

3.Can serve as individual evidence

4.Matching bullets or bullet to a firearm

comparison microscope

a compound microscope that allows the side-by-side comparison of samples, such as of hair or fibers

head stamp

Bottom of cartridge casing. Identifies caliber and manufacturer

breech mark

When a cartridge is fired, the explosion forces the bullet down the barrel and the shell casing is forced back against the breech.

chamber marks

>Caused by imperfections in the barrel chamber

>Marks are passed on to the cartridge case when it expands and is removed

extractor mark

Made when the case is pulled out of the chamber.

ejector marks

Tool marks left on a cartridge casing expelled by the ejector of a semiautomatic firearm after firing.

shotgun and shell characteristics

1.Smooth barrel

-Projectile NOT marked as it passes through

2.Fire small lead balls or pellets contained within a shell.

3.Characterized by:

-diameter of the shot

-size & shape of the wad

-Gauge: diameter of the barrel

4.Identification can still be made by comparison of extractor/ejector markings on shotgun shell.

Gun shot residue

the tiny particles expelled from a firearm when it is fired

Blow back

Primer and propellant particles blow back toward the shooter.

class evidence

material that CONNECTS an individual or thing to a certain group

individual evidence

a kind of evidence that identifies a particular person or thing

Examples Individual Evidence

1.Striae

2.Firing pin marks

3.Breech marks

4.Extractor marks

5.Ejector marks

6.Chamber marks

Examples Class Evidence

1.Bullet type

2.Bullet caliber

3.Bullet weight

4.Lands and grooves

5.Rifling

6.Cartridge case

7.Head stamp