Letter M

The Definition of Muzzle Velocity

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Muzzle Velocity

The speed of a projectile or a load of shot at the point that it exits the muzzle of a firearm, normally expressed feet per second.


19 Other Firearms Definitions You Need To Know


Terminal Ballistics

A sub-field of ballistics, is the study of the behavior of a projectile when it hits its target.

Suppressor

Incorrectoly sometimes referred to as a silencer, it is used to reduce the sound of a firearm's discharge. They do not actually silence most firearms but rather lower the intensity of the muzzle blast and change the sound characteristics (works similarly to an automotive muffler by disrupting and spreading out the sound waves). The possession, use, and transportation of silencers have been tightly controlled under federal law since 1934. Any device which reduces the sound of discharge by more than 2 dB is considered by the BATF to be a suppressor.

Prime

To prepare or charge a muzzle loader for firing.

Holographic Weapon Sight

a non-magnifying gun sight that allows the user to look through a glass optical window and see a cross hair reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode.

Twilight Sight

A rifle front sight with a extra-large, folding bead. Typically, in addition to the normal fine bead (which allows for more precision) the larger bead, while at a cost of potential accuracy, is more readily acquired in marginal light. Also called a Gloaming sight

Drift

The departure of a bullet or shot charge from the normal line of flight. This can be caused by wind or the unbalanced spinning of the bullet.

LC

Abbreviation for Long Colt

Bipod

Sometimes spelled Bi-Pod. A support device that is similar to a tripod or monopod, but with two legs. On firearms, bipods are commonly used on rifles to provide a forward rest and reduce motion. The bipod permits the operator to rest the weapon on the ground, a low wall, or other object, reducing operator fatigue and permitting increased accuracy.

Keyhole

The tendency of a bullet to tip in flight and hit a target sideways, leaving a distinctly oblong hole. This destabilization of the spinning bullet in flight is typically caused by a bullet weight inappropriate for the rate of twist of the rifled barrel, an out-of-balance bullet or its having nicked an impediment such as a blade of grass, in flight.

SxS

Abbreviation for Side-By-Side.

Gas Port

A small hole in the barrel of a gas-operated firearm through which expanding gases escape to power the autoloading system.

Light Machine Gun

A machine gun that is designed to be carried and opperated by a single person.

CQB

Abbreviation for Close Quarters Battle.

Floor Plate

The detachable plate at the bottom of the cartridge magazine.

Disc-Set Strikers

Circular steel fittings, about 1/2 inch in diameter, screwed into the breech face of a gun and through which the firing pins pass. Firing pin bushings allow the convenient replacement of broken firing pins. They also allow the renewal of an older gun where, over the decades, leakage of high-pressure gas from corrosive primers has eroded the breech face around the firing pins; and replacing these bushings with new ones, slightly oversized can compensate for a situation where proper headspace has been compromised.

Holdopen Toplever

A catch built into the receiver of a break-open gun to keep the toplever in its extreme right position when the barrels are removed. This device makes it slightly easier to remount the barrels. As the barrels are mounted and the breech closed, the barrels contact some kind of release pin (marked with the arrow) and the toplever automatically returns to the center locked position. Because, however, it requires a separate act to find and to depress this tiny tab to re-center the toplever on a broken-down gun, this feature may be irritating when trying to put a gun away in its case.

AD

Abbreviation for Accidental Discharge

Gain Twist

A form of rifling where the helical angle (pitch) sharpens progressively down the bore in the interest of maximizing the bullets ultimate rotational speed by initiating it slowly.

Recoil Crossbolt

A steel bolt, mounted transversely through a rifle stock just under and behind the front (and sometimes rear) receiver ring, sometimes concealed in the wood and usually against which the action is carefully bedded. When properly fitted, it helps distribute the recoil and reinforces stock at the point where wood has been removed to accept the action. Recoil crossbolts can be recognized by the flush-mounted circular steel fittings on the side of the stock, but are sometimes finished with contrasting wooden plugs and sometimes concealed completely. Also called Reinforcing Crossbolt.