Letter B

The Definition of Bore Diameter

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Bore Diameter

The measurement from one side of the bore to the other. In a rifled barrel this means measurement of the bore before the rifling grooves are cut.


19 Other Firearms Definitions You Need To Know


Ballistic Fingerprint

A fired case has marks upon it that it picked up from the extractor, ejector, and breechface of the gun when the shot went off. A bullet fired through a rifled barrel also has rifling marks unique to the barrel that launched it. A record of these marks, when stored in a central database, is called a ballistic fingerprint. Some states require this record to be made by law, so that individual guns can be located from bullets or casings found at the scene of a crime.

Kick

Slang for Recoil.

Nipple

A small metal tube extending through the breech of a percussion firearm through which the flame passes from the percussion cap to fire the powder charge.

Heel & Toe Plates

Protective plates, usually of steel or horn, covering the top and bottom of a gunstock's butt only (the heel and the toe); leaving wood exposed in the center

Open Sights

A common type of iron sights in which the rear sight is an open-topped U or a V or a square-notch shape and with a blade type front sight, in contrast to the closed circle commonly found in aperture sights.

Cover Garment

Any piece of clothing that covers the holstered gun. When the gun is worn on the belt, the most common types of cover garments are vests, sweaters, and jackets.

LMG

Abbreviation for Light Machine Gun

Ball

Originally used to describe the spherical projectile used in black powder firearms, now also used to refer to a fully jacketed bullet of cylindrical profile capped with a round nose

Hand-Detachable Locks

The firing mechanism of a break-open gun which may be removed for inspection or cleaning without the use of tools. The release latch may be plainly visible or concealed. A feature typically seen on sidelock guns but also on the Westley Richards "droplock" boxlock action.

Mississippi Rifle

Nickname for the U.S. M1841 Rifle, a .54 caliber muzzleloading rifle. The name comes from their use by a group of U.S. Volunteers from Mississippi who were commanded by Jefferson Davis in the Mexican War. Some were later rebored to .58 caliber.

Loading Gate

The hinged cover over the opening through which cartridges are inserted into the magazine.

Primer Pocket

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

Choke

A constriction at or near the muzzle of a shotgun barrel that affects shot dispersion.

Slide Catch

Sometimes also known as a slide lock, slide release or slide lever. On a semi-autmatic gun, the lever or catch that holds the slide open (after the last round is fired or when racking an empty gun). Typically they are located on the left side of the frame about mide barrel. Some of the newer semi-automatic pistols have an internal slide lock. Even though on pistols with an external slide catch, you can push down on the lever to release the slide, it should never be used in such a manner. The proper way to release the slide is to rack the slide.

Sling

A strap, usually of leather or sturdy webbing, fitted to the fore and aft (usually) of a rifle as an aid to carrying over the shoulder and as an aid to holding the rifle steadily while aiming.

Pellet (air gun)

Skirted projectiles used in pellet guns

Autoloader

A firearm that automatically loads the next cartridge to be fired into the chamber either upon the pull of the trigger in an open bolt design or upon the firing of the previous round in a close bolt design.
Autoloader should not be confused with Automatic or Semi-Automatic since the term Autoloader only applies to how the next round is chambered not how many rounds can be fired per trigger pull. All Automatic and Semi-Automatic firearms are autoloaders. Revolvers, bolt action, lever action and pump action firearms are not autoloaders.

Double-Barreled Shotgun

A shotgun with two barrels, usually of the same gauge or bore. The two types of double-barreled shotguns are over/under (abbreviated as O/U or OU), in which the two barrels are stacked on top of each other, and side-by-side (abbreviated as SxS), in which the two barrels sit beside each other. See photo at right for example of side-by-side double-barreled shotgun. For double-barreled guns that use one shotgun barrel and one rifle barrel, see combination gun.

Load

A charge of powder, a projectile or a cartridge. Also, to prepare a gun for firing by inserting ammunition into it.