Letter P

The Definition of Primer Pocket

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Primer Pocket

The counter bore in the center of the base of a centerfire cartridge casing in which the primer assembly is seated.


19 Other Firearms Definitions You Need To Know


Clicks

A unit of adjustment for a sight.

Snap Cap

An inert ammunition-shaped object, used in practice to simulate misfeeds and other malfunctions. Some folks also use them during dry fire practice to cushion the firing pin as it strikes.

Thumb Safety

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

Doll's Head

A rib extension on a break-open gun, ending in a circular or semi-circular shape in plan (resembling the head of a doll), mating into a similarly-shaped recess in the top of the receiver, designed to resist the tendency of the barrels to pull away from the standing breech when firing. Because an action's centerpoint of flexing when firing is at the base of the standing breech, not at the hingepin, a passive doll's head extension makes an effective extra fastener, even without additional mechanical locks operated by the opening lever.

Snap Shot

A quick shot taken without deliberate aim.

Bluing

Also spelled blueing. A passivation process in which steel is partially protected against rust, and is named after the blue-black appearance of the resulting protective finish. True gun bluing is an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite (Fe3O4), the black oxide of iron, which occupies the same volume as metallic iron. Bluing is most commonly used by gun manufacturers, gunsmiths and gun owners to improve the cosmetic appearance of, and provide a measure of corrosion resistance to, their firearms.

Trap Gun

A shotgun, often with only a single relatively-long barrel, with relatively tight choke boring and a relatively high-combed stock used for shooting clay pigeons in the game of Trap, where the birds are launched at least 16 yards ahead, usually rising and going away from the shooter at relatively low angular velocity. To better absorb recoil, a trap gun is normally heavier than a field gun because one shoots a lot but walks only a little.

Express Sights

"V" shaped rear leaf sights mounted to a rifle barrel on a block or on a quarter-rib, sometimes solid standing, sometimes folding, and often mounted in a row of similar leaves, each of a slightly different height, marked with the range for which each is regulated

Muzzle Control

Being aware of and responsible of which direction your firearm is pointed at all times, and always keeping it pointed in a safe direction.

Negligent Discharge

The unplanned discharge of a firearm caused by a failure to observe the basic safety rules, not a mechanical failure of the gun.

Martini

A hammerless single shot action type whereby a breech-block, hinged at the upper rear, operated by an underlever, tilts downward to expose the chamber.

Rimfire

Helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis. This spin serves to gyroscopically stabilize the projectile, improving its aerodynamic stability and accuracy.

Hollow-Point Bullet

A type of expanding bullet with a concavity in its nose to increase expansion on penetration of a solid target. Some hollow-point's are also designed to fragment as they expand. They are least likely to over-penetrate the target and harm an innocent bystander. Commonly used for self-defense.

Intercepting Sear

A second sear, poised just behind a second notch in the hammer. It is possible that when a cocked firearm is dropped or sharply jarred, a single sear could jump out of its notch and the hammer could fall, firing the gun accidentally. In this event, an intercepting sear would engage before the hammer could fall completely, preventing an accidental discharge. On a gun with intercepting sears, only by pulling the trigger are both sears moved out of the way simultaneously, allowing the gun to fire. Intercepting sears are usually found on better sidelock actions. They are sometimes found on best boxlocks, and can be recognized by an extra screw behind the action fences, in addition to the usual two screws (or pins) along the lower rear of the receiver.

Muffs

Slang for Ear Muffs.

Trigger

The small lever on a cartridge firearm, which one pulls to cause the spring-loaded firing pin to impact the primer, causing the gun to discharge. Normally, the trigger simply connects to the sear. Pulling the trigger moves the sear out of its notch, releasing the spring-loaded hammer to strike the firing pin which in turn strikes the primer; or the coilspring-loaded firing pin directly. Other, often-Germanic systems have their own miniature lockwork which, when cocked, allows an exceedingly light trigger pull to discharge the firearm, a setting that would be perilous to carry in the field.

Gas Vent

A passage built into a firearm to allow the safe conduct of unexpected gas, as from a pierced primer, to minimize damage both to the gun and to the shooter.

Squib

An underpowered powder charge, usually caused by a fault in cartridge loading, often insufficient to expel a projectile from the muzzle of a firearm. If such a blockage is not cleared, the next attempted shot could cause the barrel at least to bulge, and very possibly to burst.

Sight Picture

What the shooter sees when looking through the sights at the target.