Letter M

The Definition of Mag

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19 Other Firearms Definitions You Need To Know


Breechblock

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

Gape

The degree to which the barrel(s) of a break-open gun drop down; the size of the opening space, which should be sufficient to allow for ease of loading, unloading and properly-functioning ejection. A good gape is easier to achieve on a side-by-side than an over & under where the bottom barrel is well-enclosed by the action body.

Cylindro Conoidal Bullet

A hollow base bullet, shaped so that, when fired, the bullet will expand and seal the bore. It was invented by Captain John Norton of the British 34th Regiment in 1832, after he examined the blow pipe arrows used by the natives in India and found that their base was formed of elastic locus pith, which by its expansion against the inner surface of the blow pipe prevented the escape of air past it.

Cylinder

The part of a revolver that holds cartridges in separate chambers radially around a central hingepin. The cylinder revolves as the handgun is cocked, , either to the left or to the right depending on the gun maker's design, bringing each successive cartridge into position, and locked into alignment with the barrel for firing.

Lever Action

A type of firearm action which uses a lever located around the trigger guard area, (often including the trigger guard itself) to load fresh cartridges into the chamber of the barrel when the lever is worked.

Headspace Gauge

Plugs of hardened steel, precisely machined in relation to the standard dimensional specifications of a given cartridge, normally in sets of three: "GO", "No-Go" and "Field". By loading these plug-gauges into the chamber in succession, one can check that the action should close on the "Go" gauge. It should not close on the "No-Go" gauge, but might were enough force to be used. And, it absolutely should not close on the "Field" gauge.

Over Travel

If the trigger is able to continue moving to the rear after the shot has fired, the trigger is said to over-travel.

Anson & Deeley Action

A type of internal hammer side by side shotgun boxlock action. It was patented in 1875 and is the essence of simplicity utilizing only two springs and three moving parts (per barrel). One of the most successful action designs ever, and still produced to this day by most SxS shotgun manufacturers.

Failure To Feed

A semi-automatic firearm malfunction in which the slide passes entirely over the fresh round, failing to pick it up to insert into the chamber as the slide returns to battery.

Pistol Grip

The handle on a pistol. Can also refer to a vertical grip behind the trigger on a rifle.

Automatic

A type of firearm which, utilizing some of the recoil or some of the expanding-gas energy from the firing cartridge, cycles the action to eject the spent shell, to chamber a fresh one from a magazine, to cock the mainspring and to fire again. Such a firearm will fire continuously as long as the trigger is held back, until the magazine is empty. A machine gun. A firearm thus activated, but which shoots only one bullet with each separate pull of the trigger, while often erroneously referred to as "automatic" is properly termed Semi-Automatic.

Bore Axis

An imaginary line which runs right down the center of the handgun's barrel and out though the back end of the gun. A handgun may have a high bore axis, with the imaginary line running out into space well above the shooter's hand. Or it may have a low bore axis, with the imaginary line running either straight through the shooter's hand or just skimming the surface slightly above her hand. A high bore axis tends to create greater perceived recoil and more muzzle flip when firing the gun than does a low bore axis.

COF

Abbreviation for Course of Fire.

Pinfire

An early form of complete, self-contained cartridge. It included bullet, powder and ignition primer, all in one package. The primer was located towards the base of the cartridge, but completely internally. The pin, shaped like a little finishing nail, pointed on the inside end and resting on the internal primer, projected radially about a quarter-inch to the outside of the base of the cartridge. When loaded, a pinfire gun showed the tips of the pins exposed through small slots in the tops of the breech faces of the barrels. To fire, hammers fell on the pins, driving them (through the wall of the cartridge) into the internal primer.

Shooting Sticks

A pair of slender and easily-carried wooden dowels or sticks, which when held, crossed, in the fingers of the left hand while also supporting the forend of a rifle, usually shooting offhand, provides somewhat enhanced stability for a more accurate shot.

Adjustable Trigger

A trigger that can be easily adjusted by the user. Adjustable triggers are common on specialized target-shooting firearms.

Matched Pair

Two firearms that are manufactured identical in every way and are sequentially serial numbered and are sold as a set. The most common type of matched pair guns are cowboy style revolvers for a couple of reasons, both guns will feel exactly the same in the hands and they make the set more collectable.

Garniture

A deluxe set of several different associated weapons, being any combination of rifle, shotgun, various handguns, and possibly a knife or two, cased together with appropriate cleaning and loading tools.

Stripper Clip

Simple clips made of metal or sometimes plastic that hold several rounds of ammunition in a row and is used to quickly fill a magazine.