Letter H

The Definition of HMR

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19 Other Firearms Definitions You Need To Know


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.

CHL

Abbreviation for Concealed Handgun License.

Mouse Gun

A name for any palm sized handgun which fires a small caliber.

Open Frame

Refers to a revolver frame that has no top-strap over the cylinder.

Submachine Gun

A machine gun that fires pistol caliber rounds such as .45 acp or 9mm Luger (Parabellum)

Ambi

Short for the word Ambidextrous. Meaning that a feature of a firearms can be used by either hand, for example ambi-safety, ambi slide catch or ambi mag release.

Overbore Ammunition

Small caliber bullets being used in large cases. E.g. .22 bullet in a .45 acp case.

Lug

Any piece that projects from a firearm for the purpose of attaching something to it. For example barrel lugs are used to attach a break-action shotgun barrel to the action itself. If the firearm is a revolver, the term may also refer to a protrusion under the barrel that adds weight, thereby stabilizing the gun during aiming, mitigating recoil, and reducing muzzle flip. A full lug extends all the way to the muzzle, while a half lug extends only partially down the barrel. On a swing-out-cylinder revolver, the lug is slotted to accommodate the ejector rod.

Firing Line

A line, either imaginary or marked, from which people shoot their firearms down range.

Caliber

The diameter of the bore of a firearm measured as a fraction of an inch. Although such a measurement may be frequently stated in millimeters. It is correctly expressed as ".40 caliber" (note the decimal point) or as "10 millimeter" (without "caliber" or the leading decimal point). Caliber numbers when used to identify the size of the bullet a gun will file are usually followed by words or letters to create the complete name of the cartridge. These letters often represent a brand name or an abbreviation for the name of the company that first introduced the round.

Bolt Action

A type of firearm action in which the guns's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and finally a new round/shell (if available) is placed into the breech and the bolt closed.

Printing

Is when the outline of the concealed handgun may be discerned through the outer clothing.

Isosceles Stance

There are two basic variants of the Isosceles stance, the Traditional Isosceles and Modern Isosceles stance. In both Isosceles stances, the feet parallel pointing toward the target and are roughly shoulder width apart. Both arms are stretched almost equally forward with the gun centered forward, creating the triangular shape which gives the stance its name.

Cartridge Trap

A compartment built into the buttstock of a long gun, usually with a hinged cover, in which are drilled holes deep enough to hold several spare cartridges of the type suitable for use in the specific gun.

M1911

The official US military designation for the Colt .45 semiautomatic pistol adopted by the US in 1911. The gun was designed by John Moses Browning, and produced by Colt. During trials, the Browning-Colt design beat out several competing designs, including one from Savage and a .45 caliber version of the German Parabellum ("Luger"). The M1911 saw its first combat in the Philippines and then in World War I. Early use showed that it could be improved and in 1921 the M1911A1 was introduced, which featured a few changes like a reocontoured frame, shorter trigger, and a rounded backstrap. The M1911A1 remained the standard US military handgun until it was replaced in the 1980's by the Beretta M9. However, it remains very popular with civilian shooters in the US, and has been modified extensively to update it to conform to more modern theories of handgun usage.

Zeroing

The act of setting up a telescopic or other sighting system so that the point of impact of a bullet matches the sights at a specified distance.

Throat

The beginning of the bore of a rifled firearm. The transition between the chamber and the rifling. The area most vulnerable to erosion from high velocity cartridges.

Cartridge Overall Length

This is the maximum overall length the cartridge can be (and is expected to be) in order to function properly in magazines and the mag well of a bolt action rifle.

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.