Letter M

The Definition of MOA

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19 Other Firearms Definitions You Need To Know


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.

Double-Base Powder

A rapidly burning powder made by absorbing nitroglycerine into nitrocellulose (guncotton).

Hinge Pin

A short cylindrical rod of hardened steel running laterally near the front of the bar of a break-open gun's action around which the barrel hook revolves when the gun is opened. Over the decades, this pin and its complimentary hook can wear and a gun can sometimes "shoot loose" or "come off the face." The proper cure for this condition is to replace the hinge pin with a new one, slightly oversized, to compensate for wear on both itself and on the barrel hook.

Trigger Group

The entire collection of moving parts which work together to fire the gun when the trigger is pulled. It may include trigger springs, return springs, the trigger itself, the sear, disconnectors, and other parts.

Firing Pin Block

A type of internal safety that prevents the firing pin from moving forward for any reason unless the trigger is pulled.

Firing Pin

A needle like metal part of a modern firearm that gives a vigorous strike to the primer initiating the firing of the cartridge.

Direct Impingement

A type of gas operation for a firearm that directs gas from a fired cartridge directly to the bolt carrier or slide assembly to cycle the action.

Sectional Density

The relationship between a bullet's weight and its diameter. A long bullet, such as the original 7.62x54R loading for the Mosin Nagant 91/30, will have a high sectional density and consequently greater penetration than a shorter bullet of similar construction. A shorter bullet with less sectional density will have relatively less penetration, but greater knockdown power.

Hammer

The part of the gun that strikes either the firing pin or the round directly when the trigger is pulled then detonates the primer of the load and discharges the gun. Hammers may be external or internal. On a striker fired gun (a gun without a physical hammer) the firing pin is considered the hammer since it releases directly when the trigger is pulled.

Wad

A felt, paper, cardboard or plastic disk that is used in a shotshell. Also in muzzle loading, a piece of cloth used to seal the bullet in the barrel. It's purpose and function is the same as a shotgun wad.

Modern Isosceles

In the Modern Isosceles stance, the feet are roughly shoulder width apart, with the gun-side foot closer to the target than the off-side foot. The knees are flexed, and the entire body leans slightly toward the target. The shoulders are closer to the target than the hips, and the hips are more forward than the knees. The shoulders are rotated forward and the head, rather than being upright, is vultured down behind the sights. The entire body thus has an aggressively forward appearance, and is poised to move quickly if necessary.

Winchester Rim Fire

More commonly known as WRF, it is a family of rimfire cartridges designed by Winchester Repeating Arms Company

WTI

Abbreviation for Wound Trauma Incapacitation.

Side-By-Side

A shotgun with two barrels which are situated next to each other. Somtimes also abreviated as SxS.