Some Helpful Firearms Definitions

Action: Mechanical apparatus of a firearm that loads, fires, and ejects the cartridge.

Barrel: Metal pipe that guides initial flight of the bullet.

Black Powder: The old form of gunpowder invented over a thousand years ago and consisting of nitrate, charcoal, and sulfur.

Bore: The inside of the barrel. “Smoothbore” weapons (typically shotguns) have no rifling. Most handguns and rifles have “rifling”.

Breech: End of the gun barrel nearest to the action.

Breech block (or face): Back of the firing chamber.

Bullet: Projectile fired from a weapon.

Butt or buttstock: The portion of the gun which is held or shouldered.

Caliber: Diameter of the gun barrel in 1/100th of a inch.

Cartridge: Ammunition made up of casing, primer, powder, wadding and bullet.

Chamber: Enclosure that contains the cartridge when ready to fire.

Choke: A constriction of a shotgun bore at the muzzle that determines the pattern of the fired shot.

Gauge: Measure of the diameter of the barrel of a shotgun.

Hammer: The part of the action that drives the firing pin into the primer upon firing.

Lands and grooves: The spiral groves and raised positions inside a gun barrel resulting from rifling.

Magazine: Device for holding and delivering cartridges.

Magnum: Type of cartridge containing more than the standard amount of powder resulting in more power to the bullet.

Muzzle: The very end of the gun barrel where the bullet exits the weapon.

Pistol: Synonym for a handgun that does not have a revolving cylinder.

Powder: Solid explosive used to propel the bullet. Modern gun cartridges use “smokeless” powder that is relatively stable, of uniform quality, and leaves little residue when ignited. For centuries, “black powder” was used and was quite volatile (ignited at low temperature or shock), was composed of irregularly sized grains, and left a heavy residue after ignition, requiring frequent cleaning of bore.

Primer: Shock sensitive compound that ignites the main charge of a cartridge upon being struck.

• Revolver: Handgun that has a cylinder with holes to contain the cartridges. The cylinder revolves to bring the cartridge into position to be fired. This is “single-action” when the hammer must be cocked before the trigger can fire the weapon. It is “double-action” when pulling the trigger both cocks and fires the gun.

Rifling: The spiral grooves or polygonal interior shape inside a gun barrel.

Sight: Device on top of a gun that improves aim and accuracy.

Silencer: Device, placed over the muzzle, that reduces the noise emitted when the weapon is fired.

Single-action: The hammer must be manually cocked before the trigger can be pulled to fire the gun.

Smokeless powder: Refers to modern gunpowder, which is really not “powder” but flakes of nitrocellulose and other substances. Not really “smokeless” but much less so than black powder.

Stock: Frame holding the barrel and action together which allows aiming and firing.