chap 9 forensics

Firearms Identification

Discipline determining if a bullet or cartridge was fired by a particular weapon.

Ballistics

Study of a projectile in motion.

Single-shot Pistols

Firearms that fire only one round at a time.

Revolvers

Handguns featuring several firing chambers within a revolving cylinder.

Semi-automatic Pistols

Handguns featuring a removable magazine, firing one shot per trigger pull.

Shotguns

Long guns with a smooth barrel, firing shells containing numerous ball-shaped projectiles called slugs.

Rifles

Long guns with barrels featuring lands and grooves, impressing bullets with these markings during firing.

Gauge

Measurement of shotgun barrel diameter; higher gauge numbers indicate smaller diameter.

Lands

The surfaces between grooves inside a gun barrel.

Grooves

Spiral indentations in a barrel guiding bullets and imparting spin.

Rifling

The process of impressing spiral grooves into a gun barrel.

Striations

Fine lines in the barrel's interior that create individual characteristics on a bullet.

Caliber

Diameter of a gun barrel measured between opposite lands.

Individualization (Firearms)

Process of matching striation markings to determine if a bullet traveled through a specific barrel.

Firing Pin

Component of a firearm striking the primer to ignite gunpowder.

Breechface

Surface of the firearm against which the cartridge case is pushed during firing.

Distance Determination

Estimation of the distance between firearm muzzle and target based on residue patterns.

Bullet Wipe

Dark ring around a bullet hole resulting from a weapon fired more than 3 feet away.

Gunpowder Residue

Deposits of unburned or partially burned gunpowder expelled from a firearm.

Primer Residue

Traces of lead, barium, and antimony deposited on the shooter's hand upon firing a weapon.

Greiss Test

Chemical test used to detect invisible gunpowder residues.

Serial Number Restoration

Technique of restoring obliterated serial numbers through chemical etching.

Tool Marks

Impressions or abrasions caused by tools making contact with other objects, characterized by class and individual imperfections.

Comparison Microscope

Instrument used for comparing tool marks or bullet striations.

Casting (Impressions)

Method of preserving impressions, such as shoe or tire marks, by creating a physical cast.

Chemical Enhancement

Method to visualize faint or invisible bloody impressions.

Firearm Safety Rule 1

Always keep the firearm pointed in a safe direction.

Firearm Safety Rule 2

Treat all firearms as if they were loaded.

Firearm Safety Rule 3

Keep your trigger finger outside the guard until ready to fire.

Firearm Safety Rule 4

Be certain of your target and what lies beyond it.

Firearm Safety Rule 5

Wear appropriate eye and ear protection when using firearms.