Letter S

The Definition of Sight Radius

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Sight Radius

The distance between the rear sight and the front sight. As a longer lever provides greater mechanical advantage, the greater the distance between the two sights, the more inherently accurate they will be.


19 Other Firearms Definitions You Need To Know


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.

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.

Bureau of Alcohol, Tobacco, Firearms and Explosives

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF, BATF, and BATFE) is a federal law enforcement organization within the United States Department of Justice. Its responsibilities include the investigation and prevention of federal offenses involving the unlawful use, manufacture, and possession of firearms and explosives; acts of arson and bombings; and illegal trafficking of alcohol and tobacco products. The ATF also regulates via licensing the sale, possession, and transportation of firearms, ammunition, and explosives in interstate commerce. Many of ATF's activities are carried out in conjunction with task forces made up of state and local law enforcement officers, such as Project Safe Neighborhoods. ATF operates a unique fire research laboratory in Beltsville, Maryland, where full-scale mock-ups of criminal arson can be reconstructed.

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.

Pump Action

A type of mechanism for removing a spent shell casing from the chamber of a firearm and inserting a fresh cartridge into the chamber. This type of mechanism is most commonly used in shotguns and rimfire rifles.

Back Action

A sidelock action where the mainspring is mounted rearward towards the butt. The back action is often used in double rifles where the need for strength requires as little steel as possible be removed from the bar of the action.

Carry

Slang for a gun or the action of carrying a gun concealed, e.g "The Bersa Thunder .380 is a fantastic gun for carrying" or "Do you carry?".

Ogive

A type of curve represented by the curved section of a bullet between its bearing surface and its tip.

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.

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.

Blank

A type of cartridge for a firearm that contains gunpowder but no bullet or shot. When fired, the blank makes a flash and an explosive sound (report). Blanks are often used for simulation (such as in historical reenactments, theatre and movie special effects), training, and for signaling (see starting pistol). Blank cartridges differ from dummy cartridges and snap caps, which are used for training or function testing firearms; these contain no primer or gunpowder, and are inert.

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.

Brady Law

Brady Handgun Violence Prevention Act of 1993. The Brady Handgun Violence Prevention Act of 1993 mandates background checks of gun buyers in order to prevent sales to people prohibited under the Gun Control Act of 1968 legislation. Requires checks to be performed through the FBI's National Instant Criminal Background Check System (NICS). Records of who has been checked are not preserved because federal law prohibits the creation of a national registry of gun ownership. Sales by unlicensed private sellers who are not engaged in gun dealing as a business are not subject to the checks under federal law, though they are required by some states.

Gun

A firearm.

Small Arms

Firearms designed to be carried and used by an individual or individuals.

Sporting Firearm

Any gun that can be used in a sport.

Inletting

The process of carving out recesses in wooden stocks with precision, using gouges, chisels and scrapers to accept the steel components of a firearm.

Interrupted Thread

A screw with about half of its threading removed in longitudinal sections. Often used at the breech end of a takedown firearm's barrel. When the barrel's interrupted female threads are inserted into the receiver's complementary interrupted male threads, only a partial rotation is necessary for assembly rather than many full turns.

Biathlon

A shooting sport that combines both skiing and rifle shooting. It is the only shooting activity in the Winter Olympics. There is also a summer biathlon which involves running and shooting but it is not yet an Olympic event.