Firearms Definitions You Need To Know

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Rim

The edge on the base of a cartridge case which stops the progress of the case into the chamber.

Half Cock

A middle position for an external hammer that effectively provides a safety function. With a firearm with non-rebounding hammers, when on half-cock, the firing pin will not rest on the firing-pin.

Small Bore

Generally refers to a .32 calibre or smaller firearm.

Monte Carlo Comb

The Monte Carlo comb came to rifles via shotgun stocks. It rises well above the ordinary comb line of the stock at the butt and tapers downward toward the point of the comb. This raised portion of the stock lifts the face of the shooter and his or her line of sight well above the standard elevation provided by the classic style. However, the same amount of drop is maintained at the buttstock. A shooter with a long neck who often has trouble getting his or her face down far enough on the comb of the regular stock benefits from the Monte Carlo style.

Overbore Ammunition

Small caliber bullets being used in large cases. E.g. .22 bullet in a .45 acp case.

Cocked

A state of readiness of a firearm. The hammer (or similar mechanism if there is no hammer) only needs to be released by the trigger to cause the gun to fire.

Reflector Sight

A generally non-magnifying optical device that has an optically collimated reticle, allowing the user to look through a partially reflecting glass element and see a parallax free cross hair or other projected aiming point superimposed on the field of view. Invented in 1900 but not generally used on firearms until reliably illuminated versions were invented in the late 1970s (usually referred to by the abbreviation "reflex sight").

LFX

Abbreviation for Live Fire Exercise

Sporting Clays

A shotgun shooting sport that combines elements of skeet and trap, and that is designed to simulate field conditions.

Speed Loader

A device used to load magazines or revolver cylinders quicker than by hand.

Four Rules

The four rules of firearms safety,were originally introduced in the early 1900's by various shooting education sources (with varying phrasing, but same implications), they apply every single time a firearm is handled in any way or for any reason. The NRA teaches the Three Rules of Safe Gun Handling.

Rule One: All guns are always loaded. (Treat all guns as if they are loaded, no matter what!)
Rule Two: Never point your firearm at anything you are not willing to destroy.
Rule Three: Never put your finger on the trigger unless your sights are on target (and you have made the decision to fire).
Rule Four: Be sure of your target and what is behind it.

Railgun

A railgun is an electrically powered electromagnetic projectile launcher based on similar principles to the homopolar motor.
Using a magnetic field powered by electricity, a rail gun can accelerate a projectile up to 52,493 feet (16,000 meters) per second.
A railgun consists of two parallel metal rails (hence the name) connected to an electrical power supply. When a conductive projectile is inserted between the rails (at the end connected to the power supply), it completes the circuit. Electrons flow from the negative terminal of the power supply up the negative rail, across the projectile, and down the positive rail, back to the power supply.

Improved Cartridge

A wildcat cartridge that is created by straightening out the sides of an existing case and making a sharper shoulder to maximize powder space. Frequently the neck length and shoulder position are altered as well. The caliber is NOT changed in the process.

Center Of Mass

For self-defensive shooters, Center Of Mass (COM) represents the area of an attackers torso within which the most vital organs are likely to be disrupted by a gunshot. Shooting to COM is considered the most expedient way to stop an assailant from continuing threatening behavior.

BUG

Abbreviation for 'Back Up Gun'

Limp Wristing

A floppy, limp wrist while shooting.

Submachine Gun

A machine gun that fires pistol caliber rounds such as .45 acp or 9mm Luger (Parabellum)

Pinfire

An early form of complete, self-contained cartridge. It included bullet, powder and ignition primer, all in one package. The primer was located towards the base of the cartridge, but completely internally. The pin, shaped like a little finishing nail, pointed on the inside end and resting on the internal primer, projected radially about a quarter-inch to the outside of the base of the cartridge. When loaded, a pinfire gun showed the tips of the pins exposed through small slots in the tops of the breech faces of the barrels. To fire, hammers fell on the pins, driving them (through the wall of the cartridge) into the internal primer.

High Kneeling

A shooting position in which one or both knees are touching the ground, but the shooter is otherwise erect.

Bullet Trap

A type of backstop that catches the fired bullet and prevents it from exiting the area. Bullet traps are most commonly used on indoor ranges.