Parts of a Firearm

The process of loading, firing, extracting, and ejecting ammunition in a firearm.

• Bolt: an action type in a firearm where a bolt that is parallel to the bore is used to operate the firearm; the bolt manually reciprocates to load, unload, and cock the firearm.
• Lever: an action type in a firearm where a lever is used to drive the mechanism for loading the cartridge.
• Pump: an action type in a repeating firearm where the movement of the slide/pump is used to manually set the firearm, and performs all of the assigned functions of the firing cycle.
• Revolver: a repeating firearm where a revolving cylinder is used to hold the ammunition in several chambers and must reciprocate along an axis to introduce the ammunition into the barrel.
• Semi-automatic: an action type in a repeating firearm where the trigger needs to be pulled for each projectile to be fired, but uses the energy of the discharge to assist in performing other parts of the operation.
• Single-shot: a firearm that requires manual loading after each discharge as it does not have a magazine or means to store or load ammunition.
• Single-action: a revolver where a hammer must be manually cocked prior to pulling the trigger between each discharge.

A hollow tube through which the projectile travels after being discharged; may contain rifling.

The rear end of the barrel which supports the base of the cartridge.

1. Firearm: a measure of the diameter of the bore in a firearm.
2. Cartridge case: a measure of the diameter of the bullet it is capable of being loaded with, followed by a name associated with its dimensions.
3. Bullet: a measure of the diameter of the bullet.

A cartridge in which the primer is found in the center of the base of the case in a separate self-contained component.

It is a cavity before the barrel where the ammunition is first loaded before being fired.

The projectile leaves the barrel with the spin; when it hits a surface at an acute angle it contacts the surface whilst spinning we see a rotational marking on the targeted surface.

A microscope that is essentially two compound microscopes attached by an optical bridge allowing the view of two separate objects to be viewed side by side simultaneously; commonly used in firearm/toolmark analysis.

The process through which a firearm is discharged.

• Cocking: process used to cock the firing pin/hammer to allow striking of the primer.
• Loading: process that loads a cartridge from the magazine to the chamber.
• Firing: process that allows the primer at the base of the cartridge to be impacted by the firing pin and ignite the powder.
• Extraction: process that allows the discharged cartridge case to be removed from the chamber.
• Ejection: process that removes the discharged cartridge case from the firearm and cocks the firing pin/hammer for the next round.

The part of a revolver consisting of several chambers rotating on its axis, that holds the cartridges.

A component that strikes the fired cartridge case as it is being extracted from the chamber, and ejects it out of the firearm.

The part of a firearm that grasps the rim of the cartridge and assists in extraction of the cartridge case after discharge.

A component of the firearm that is used to strike the primer of the cartridge.

The raised parts of the rifling in the barrel of a firearm.

Perpendicular force to the plane of a surface on which a depression is being made.

The depressed parts of the rifling in the barrel of a firearm.

A part of a repeating firearm that stores the cartridges and consists of a mechanism that allows the loading of the cartridge into the chamber of the firearm.

The opening at the end of the barrel from where the bullet or shot emerges and leaves the firearm.

A component of the cartridge that is the portion of the cartridge that takes flight when firing a firearm; can be a bullet, slug, or any component used to be propelled upon discharge.

The compound in the cartridge that ignites the powder of the cartridge when struck.

The chemical composition that generates gas when ignited by the primer. The gas propels the projectile(s). Also known as gunpowder.

As a projectile is making impact on a painted metal surface, it is a small area of surviving paint at the initial point of contact between surface and projectile.

Spiral series of lands and grooves that are cut or formed into the bore of a firearm to give the fired projectile a spin to increase its stability, accuracy, and range.

The basic unit of a firearm which houses the firing mechanism and to which the barrel and stock/grip are assembled.

A cartridge in which the primer is found along/inside the rim of the cartridge.

The wood/plastic/polymer component to which the metal parts of a firearm are attached, to enable the shooter to hold the firearm.

Any instrument designed to reduce the sound of the discharge; also known as silencer.

A component typically found in semiautomatic pistols, that moves in line with the axis of the bore during the cycle of fire. The slide generally houses the firing pin/striker and the extractor.

A large single projectile used in shotguns.

A cartridge that is used in a shotgun; often a centrefire and contains multiple pellets or a slug.

Spherical projectiles in a shotshell typically composed of lead, steel, tin, zinc etc, that are released upon discharge. Useful for shorter range targets and hunting.

The force applied to an object is almost parallel to the plane on which the striations are being made.

A paper, felt, cardboard or plastic component in a shotshell that is used to separate the powder charge and the shot/slug; helps hold the propellant gases behind the projectile and keep the shot together in the barrel.

A wave like pattern seen when a projectile impacts a metallic painted surface. It can help indicate direction of projectile travel.