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


Bore Snake

A bore snake is a tool used to clean the inside (bore) of the barrel of a gun. It resembles a short section of rope with a smaller, weighted cord attached to one end to help feed the bore snake through the barrel. A bore snake often has one or more integrated brushes to help clean the barrel, and may also be used to apply lubricant. It is an alternative to using a cleaning rod and patches to clean the barrel of a gun. Bore snakes are made in different sizes for different calibers and gauges of guns.

Monoblock Barrels

A method of building a pair of barrels where the entire breech end of both barrels and the lumps together are machined from one solid piece of steel. The barrel tubes are then fitted separately into this monoblock and the ribs attached. Often identifiable by a distinctive ring around the barrels about three inches in front of the breech end. The favored jointing method of the Beretta company. An incorrect euphemism for sleeved barrels.

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.

Ejection Port

The opening through which the empty, spent ammunition case is ejected from of a firearm.

Touch Hole

A small orifice at the breech end of the barrel of a muzzle-loading firearm through which the exploding priming charge is conducted from the flash pan to the main charge.

Cover

Anything a person can hide behind that will probably stopp a bullet.

Underhammer

A type of lock in which the hammer pivots in a vertical arc, striking the nipple on the underside of the barrel. Since the nipple's flash channel goes straight into the powder at the breech end of the barrel, ignition time is very fast. For this reason, and because it gets the hammer out of the way, underhammer locks are commonly used on muzzleloading benchrest rifles which are used for target shooting, and where accuracy is the goal.

Scope Blocks

A pair of small dovetailed steel bases, screwed usually one to the barrel and one to the front receiver ring of a rifle, to accept mounts for target scopes such as the Unertl where the scope is allowed to move forward in the rings under the recoil of the rifle and which typically carry the windage and elevation adjustments in the mount.

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.

Plinking

Informal shooting at any of a variety of inanimate targets.

Hood

Front sight hood. A hollow cylinder fitted to a rifle's front sight ramp, both to protect the delicate front sight bead from impact, and to shade it from oblique sunlight which could have the effect of altering the sight's apparent position.

Front Sight

The front sight is placed at the muzzle end of the barrel. It is often (but not always) in the form of a dot or a blade. To attain a proper sight picture and shoot with the greatest degree of accuracy, the shooter's eye should be focused sharply upon the front sight while shooting, allowing both the rear sight and the target to blur somewhat.

Revolver

A repeating firearm in which the ammunition is held in a multi-chambered cylinder, which is rotated to bring each chamber in line with the barrel. Most revolvers are handguns, although shoulder-fired arms have been made using this sort of mechanism.

Grooves

The cut-away, concave portions of the rifling inside the barrel of a firearm discharging a single projectile.In other words, the lower portion of rifling.

Ears

Slang for hearing protection. Applies to either muffs or plugs.

Breechblock

The part in the breech mechanism that locks the action against the firing of the cartridge.

AR

Contrary to some people's belief, AR does NOT stand for Assault Rifle. The designation AR stands for the original designing company ArmaLite.
An AR is a firearm platform originally designed by ArmaLite and built by Colt, an AR is a lightweight, intermediate cartridge magazine-fed, air-cooled rifle with a rotating lock bolt, actuated by direct impingement gas operation or long/short stroke piston operation. It has been produced in many different versions, including numerous semi-automatic and selective fire variants. It is manufactured with extensive use of aluminum alloys and synthetic materials. Types of ARs include AR-15, AR-10 and AR-7.

Ejection Rod

The sliding metal dowel located at the muzzle end of a revolver cylinder. After firing, the shooter opens the cylinder and depresses the front end of the ejection rod, which forces the empty cases out of the cylinder.

Frangible

A bullet that is designed to disintegrate into tiny particles upon impact to minimize their penetration for reasons of range safety, to limit environmental impact, or to limit the danger behind the intended target. Examples are the Glaser Safety Slug and the breaching round.