Letter U

The Definition of Under Barrel

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Under Barrel

The bottom barrel on an Over/Under shotgun.


19 Other Firearms Definitions You Need To Know


Dram

A unit of measure traditionally used for black powder shotgun charges. Today, used for smokeless powders on the basis of the new propellant's equivalent performance to that weight of black powder. Thus, a shotgun shell marked 3 - 1 1/8 would be loaded with the smokeless powder equivalent of 3 drams of black powder, and with 1 ounce of shot. 1 Dram = 1/16 ounce = 437.5 grains.

Pellet Gun

An air gun that shoots a skirted pellet.

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.

Knurled Surface

A metal surface which contains a pattern of ridges or beads.

GCA

Gun Control Act of 1968. It is a U.S. federal law that regulates the firearms industry and firearms owners. It primarily focuses on regulating interstate commerce in firearms by generally prohibiting interstate firearms transfers except among licensed manufacturers, dealers and importers. It also prohibits all convicted felons, drug users and the mentally ill from buying guns amd raised the age to purchase handguns from a federally licensed dealer to 21.

Dry Fire

To pull the trigger and release the hammer of a firearm without having a cartridge in the chamber.

Dummy Round

An inert ammunition-shaped object, used in practice to simulate misfeeds and other malfunctions and also used in dry fire practice. Unlike a blank, a dummy round contains no charge at all. A snap-cap is a type of dummy round.

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.

Toplever

A lever on a break-open gun mounted to the top of the receiver which, when pushed with the thumb (normally) to the right, operates (usually) a Scott Spindle, which in turn withdraws (usually) a Purdey Underbolt from the bites in the lumps of the barrels, allowing them to hinge downwards and the gun to open.

Speedloader

A device used to reduce the time and/or effort needed to reload a firearm's magazine.

Rim

The edge on the base of a cartridge case which stops the progress of the case into the chamber.

Jam

A malfunction which locks up the gun so badly that tools are required in order to fix it. Sometimes used to denote a simple malfunction, but many people make a distinction between a complete jam and a simple malfunction.

Patch Box

Covered compartment in the buttstock of a muzzle-loading rifle used to carry patches or other small items.

Lede

The bevelled portion of the rifling at the rear end of the barrel (and the forward portion of the chamber) where the bullet first engages the lands.

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.

Fouling

The accumulation of unwanted material on solid surfaces. The fouling material can consist of either powder, lubrication residue, or bullet material such as lead or copper.

Loading Gate

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

Over-Under

Can also be spelled Over/Under, OverUnder or Over and Under. A firearm (most commonly a shotgun) with two barrels that are vertically aligned with each other, one on top of the other.

Shotgun Shell

The cartridge for a shotgun. It is also called a "shell," and its body is usually made of plastic (metal shotgun shells are very rare, paper shotgun shells are extinct) with a metal head. Small shotshells are also made for rifles and handguns and are often used for vermin control.