Firearms Evidence Terminology

Flashcards covering key vocabulary and concepts related to firearms evidence.

PISTOL

A handgun, most common type now days, a semi-automatic, which uses a magazine and ejects fired cartridge cases automatically.

REVOLVER

A handgun that has a rotating cylinder to hold cartridges for firing, cartridge cases not ejected automatically, must do by hand.

SHOTGUN

A shoulder-fired firearm with a smooth barrel.

RIFLE

A shoulder fired firearm with a rifled bore.

BALLISTICS

Scientific study of the motion of projectiles (the study of bullets)

BULLET

The projectile that is expelled from a rifled firearm. Not a slug.

CARTRIDGE

A complete unfired round of ammunition (casing, projectile, primer and powder).

FIRING PIN

The working component of a firearm that contacts the ammunition.

GROOVE

Interior portion of a rifled barrel that is cut to form the rifling.

LAND

The interior portion of a rifled barrel between two grooves.

RIFLING

Grooves in the interior of a firearm barrel to impart spin to a bullet.

SHOTGUN SHELL

A complete unfired round of a shotgun, consists of casing, projectile, wadding, primer and powder. Also called a slug.

WADDING

Paper or plastic in shotgun shell that forms a seal between the powder and the shot.

HEADSTAMP

The markings on the bottom of a cartridge case designed for a firearm. Tells the manufacturer and caliber.

CASE

The container that holds all the other ammunition components together.

GUNPOWDER

A chemical mixture that burns rapidly and converts to an expanding gas when ignited.

PRIMER

An explosive chemical compound that ignites the gunpowder when struck by a firing pin.

PROJECTILE

The object(s) expelled from the barrel.

WAD

Seal and/or shot container made of paper or plastic separating the powder from the slug or shot in a shotshell.

Types of Ballistics

Ballistics is classified into four types, they are Internal Ballistics, Transitional Ballistics, External Ballistics and Terminal Ballistics

INTERNAL BALLISTICS

Deals with what takes place in a duration of about two milliseconds from the point of firing the pin or striker, to the exit of the bullet through the muzzle end of the barrel.

TRANSITIONAL BALLISTICS

Involves the mediator between two regimes (internal and external ballistics).

EXTERNAL BALLISTICS

It is concerned with the flight of the bullet after leaving the barrel.

TERMINAL BALLISTICS

Deals with the impact of projectiles.

Laceration and crushing

Tissue damage through laceration and crushing occurs along the path or track through the body that a projectile, or its fragments, may produce.

Cavitation

A permanent cavity is caused by the path (track) of the bullet itself with crushing of tissue, whereas a temporary cavity is formed by radial stretching around the bullet track from continued acceleration of the medium in the wake of the bullet, causing the wound cavity to be stretched outward.

Shock waves

Compress the medium and travel ahead of the bullet, as well as to the sides, but these waves last only a few microseconds and do not cause profound destruction at low velocity.