Letter A

The Definition of Annulus

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Annulus

A tiny circular recess at the base of a cartridge case surrounding the primer pocket. Recoil from fired cartridges invariably impress a discernable ring on the breech or bolt face of a firearm, providing some evidence of the amount of use it has seen.


19 Other Firearms Definitions You Need To Know


Knuckle

The curved, forward end of the bar of a break-open firearm's action, about which the mounted forend iron revolves downward. This area should be kept lightly greased to avoid galling the bearing surfaces.

Makarov

The Soviet Union's standard military and police side arm from 1951 to 1991 replacing the Tokarev TT-33 semi-automatic pistol and the Nagant M1895 revolver. Designed by Nikolay Fyodorovich Makarov, it is a blowback operated semiautomatic pistol which fires the 9x18mm Makarov cartridge, and holds 8 rounds in the magazine.

Fulminate Of Mercury

A highly sensitive explosive used as a primer compound.

Slide Lever

A slang term for slide catch.

Hornady Magnum Rimfire

A type rimfire rifle cartridge developed by the ammunition company Hornady. .17 Hornady Magnum Rimfire (4.527mmR), commonly known as the .17 HMR, was developed in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber (4.5 mm) bullet.

Flinch

To jerk a firearm off target inadvertently in the instant of firing in timid anticipation of recoil. Commonly caused by learning to shoot with a gun more powerful then they are ready for.

Dram

A unit of measure traditionally used for black powder shotgun charges. Today, used for smokeless powders on the basis of the new propellant's equivalent performance to that weight of black powder. Thus, a shotgun shell marked 3 - 1 1/8 would be loaded with the smokeless powder equivalent of 3 drams of black powder, and with 1 ounce of shot. 1 Dram = 1/16 ounce = 437.5 grains.

GCA

Gun Control Act of 1968. It is a U.S. federal law that regulates the firearms industry and firearms owners. It primarily focuses on regulating interstate commerce in firearms by generally prohibiting interstate firearms transfers except among licensed manufacturers, dealers and importers. It also prohibits all convicted felons, drug users and the mentally ill from buying guns amd raised the age to purchase handguns from a federally licensed dealer to 21.

Ballistics

The science of cartridge discharge and the bullet's flight. Internal ballistics deals with what happens inside of a firearm upon discharge. External ballistics is the study of a projectile's flight, and terminal ballistics is the study of the impact of a projectile.

Kurtz

German for "short." Seen as part of a cartridge designation. On some German manufactured guns that use .380 ACP, the designated caliber is 9mm Kurtz (9mm Short), which is also the same as the Italian 9mm Corto

Mortar

An artillery piece used to fire shells over short ranges at very high trajectories.

Die

A piece of tooling used to form a sequence of uniform parts through the use of heat and/or pressure; especially, in firearms terminology used to form brass cartridge cases accurately to their correct size for reloading.

Clicks

A unit of adjustment for a sight.

Patch Box

Covered compartment in the buttstock of a muzzle-loading rifle used to carry patches or other small items.

Thumb Safety

An external, manual safety which is typically disengaged with the firing-hand thumb.

Recoil

The tendency of a firearm when fired to move backwards, and a little upwards as a reaction to the force of the projectile moving down the barrel. As Newton says, to every action there is always an equal and opposite reaction. The mass of the firearm provides some inertia to counteract the momentum of recoil. What remains is absorbed by at the shoulder or the hand. The heavier the gun, the less the recoil. The more powerful the cartridge, the more the recoil.

Trigger Pull Weight

The ammount pressure needed (measured in pounds) for the trigger finger must put on the trigger before the gun will fire. Trigger pull weight is measured by the number of pounds and ounces of pressure required to pull the trigger past the break.

Magazine Safety

A mechanism that prevents the gun from being able to fire when the magazine is removed from the gun, even if there is still a round in the chamber.

Riot Gun

A popular term for a short barreled repeating shotgun as frequently used in law enforcement and personal protection.