Firearm Glossary

Term Definition

blowback: A system of operation for self-loading firearms that obtains power from the motion of the cartridge case as it is pushed to the rear by expanding gases created by the ignition of the powder charge


blank: A type of cartridge for a firearm that contains gunpowder but no bullet or shot. When fired, the blank makes a flash and an explosive sound (report). Blanks are often used for simulation (such as in historical reenactments, theatre and movie special effects), training, and for signaling (see starting pistol). Blank cartridges differ from dummy cartridges, which are used for training or function testing firearms; these contain no primer or gunpowder, and are inert.

black powder substitute

black-powder substitute: A firearm propellant that is designed to reproduce the burning rate and propellant properties of black powder (making it safe for use in black-powder firearms), while providing advantages in one or more areas such as reduced smoke, reduced corrosion, reduced cost, or decreased sensitivity to unintentional ignition.

black powder

black powder also called gunpowder: a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing a volume of hot gas made up of carbon dioxide, water, and nitrogen, and a solid residue of potassium sulfide.Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. Modern firearms do not use the traditional black powder described here, but instead use smokeless powder.


barrel: A tube, usually metal, through which a controlled explosion or rapid expansion of gases are released to propel a projectile out of the end at high velocity.

ballistic coefficient

ballistic coefficient or BC: a measure of projectiles ability to overcome air resistance in flight. It is inversely proportional to the deceleration—a high number indicates a low deceleration. BC is a function of mass, diameter, and drag coefficient. In bullets, it refers to the amount that drop over distance and wind drift affects the bullet.


ammunition or ammo: Gunpowder and artillery. Since the design of the cartridge, the meaning has been transferred to the assembly of a projectile and its propellant in a single package.


action: The physical mechanism that manipulates cartridges and/or seals the breech. The term refers to the method in which cartridges are loaded, locked, and extracted from the mechanism. Actions are generally categorized by the type of mechanism used. A firearm action is technically not present on muzzleloaders as all loading is done by hand. The mechanism that fires a muzzle-loader is called the lock.

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