Forensic Ballistics

The application of firearm, ammunition, projectile, and related scientific examinations to questions arising in legal investigations.

The study of processes occurring inside a firearm from ignition until the projectile exits the muzzle.

The study of a projectile's motion after leaving the muzzle and before striking a target.

The study of a projectile's interaction with a target, including penetration, deformation, and energy transfer.

To hold and support the cartridge in position for firing.

The interior passage through which a projectile travels.

A pattern of spiral lands and grooves in a barrel that imparts spin to a projectile.

A raised portion of the barrel's interior surface between adjacent grooves.

A recessed portion of the barrel's interior surface between adjacent lands.

The direction in which rifling spirals along the barrel, ordinarily described as right-hand or left-hand.

The distance along a barrel required for the rifling to complete one revolution.

Spin can provide gyroscopic stability and reduce uncontrolled tumbling during flight.

A designation associated with a firearm's bore or ammunition dimensions, although nominal caliber names do not always equal exact measured diameters.

Caliber generally describes bore or ammunition dimensions, while shotgun gauge traditionally relates to the number of equal-sized lead balls of bore diameter weighing one pound.

The forward opening of the barrel through which the projectile exits.

The rear portion of the barrel or action where the cartridge is positioned and supported during firing.

To strike or otherwise activate the cartridge primer during the firing sequence.

To initiate ignition of the propellant when activated by the firearm's firing mechanism.

To produce expanding gases through controlled combustion that propel the projectile through the barrel.

Cartridge case, primer, propellant, and projectile.

The ammunition component that holds the primer, propellant, and projectile together and supports them during firing.

Centerfire ammunition has a primer positioned centrally in the case head, while rimfire ammunition has priming compound distributed within the case rim.

To engage and withdraw a cartridge case from the chamber during the firearm's operating cycle.

To help expel a cartridge case or cartridge from the firearm's action.

A pattern transferred to a cartridge case head when it contacts the firearm's breechface under firing pressure.

A mark left on a primer or cartridge case by the firearm's firing pin.

A mark that may be produced when the extractor contacts or grips a cartridge case.

A mark that may be produced when the ejector contacts a cartridge case during ejection.

A surface mark on a cartridge case caused by contact with features of the firearm's chamber.

A mark potentially produced when a cartridge contacts the retaining lips of a firearm magazine.

A mark potentially produced when a cartridge or projectile contacts the firearm's feeding surface.

Features associated with a design or manufacturing group, such as caliber, number of lands and grooves, and rifling direction.

Microscopic features arising from manufacturing variation, wear, or damage that may help distinguish particular firearm surfaces.

Features shared by some items produced through a common manufacturing process that may resemble individual characteristics.

They can create similarities between different firearms and may lead to unsupported source conclusions if mistaken for individual detail.

A linear surface mark that may result from contact between the projectile and features of the firearm barrel.

A mark formed when one surface presses against another and transfers surface detail.

A mark formed through sliding contact that produces approximately parallel lines or grooves.

The speed of a projectile as it exits the firearm's muzzle.

The energy of motion of a projectile, calculated as one-half of its mass multiplied by the square of its velocity.

KE = 1/2 mv², where m is mass in kilograms and v is velocity in meters per second, producing energy in joules.

360 joules, calculated as 0.5 × 0.008 × 300².

The angle between a projectile's longitudinal axis and its direction of travel.

A loss or alteration of stable orientation in which the projectile rotates substantially away from nose-forward flight.

A change in the projectile's original shape caused by impact or other forces.

The separation of a projectile into two or more pieces during impact or interaction with a target.

The deflection or rebound of a projectile after striking a surface.

Deformation, nominal caliber conventions, and overlapping projectile dimensions can prevent unique identification.

No. These are broad characteristics; a supported source conclusion requires appropriate comparison of more discriminating marks.

Class characteristics that may help narrow possible firearm types but do not uniquely identify one firearm.