Letter J Firearms Glossary

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Jacket

A metal, usually copper, wrapped around a lead core to form a bullet.

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.

Jaws

The vise-like device on a flintlock hammer used to hold the flint.

Jeweling

A cosmetic process to enhance the looks of firearm parts, such as the bolt. The look is created with an abrasive brush and compound that roughs the surface of the metal in a circular pattern.

JSP

Abbreviation for jacketed soft point

Jump

The amount of change in the bore axis, measured both vertically and horizontally, while the projectile moves from the chamber to the muzzle when it is fired.


14 Other Firearms Definitions You Need To Know


Blown Pattern

A shotgun pattern with erratic shot distribution, generally caused by gas escaping past the wads and getting into the shot.

Electronic Hearing Protection

Ear muff or ear plug hearing protection that have internal electronics that amplify human voices while excluding all noises louder than a given decibel rating. Electronic hearing protection is best used when shooting outdoors. When on an indoor range they have a tendency to pick up too much echo and other muffled sounds.

Trigger Scale

A specialized type of hanging scale designed to test trigger pull weight.

Slide Release

A slang term for slide catch.

Percussion Cap

A small metal explosive-filled cup which is placed over the nipple of a percussion firearm. As the cap is struck by the hammer, it explodes and sends a flame through the flashhole in the nipple to the main powder charge.

SMLE

Abbreviation for Short Magazine Lee Enfield. The standard British Army rifle from around 1895 to 1957.

CQC

Abbreviation for Close Quarters Combat.

Railgun

A railgun is an electrically powered electromagnetic projectile launcher based on similar principles to the homopolar motor.
Using a magnetic field powered by electricity, a rail gun can accelerate a projectile up to 52,493 feet (16,000 meters) per second.
A railgun consists of two parallel metal rails (hence the name) connected to an electrical power supply. When a conductive projectile is inserted between the rails (at the end connected to the power supply), it completes the circuit. Electrons flow from the negative terminal of the power supply up the negative rail, across the projectile, and down the positive rail, back to the power supply.

Crane

A swing-out arm on a revolver, to which the cylinder is mounted when opened facilitates loading and cleaning.

Heavy Machine Gun

A larger class of machine gun..

Rifling

Spiral grooves formed into the bore of a gun barrel, which cause the bullet to spin upon firing, thus stabilizing it much like a thrown football. Rifling may be cut, swaged, or forged into the barrel.

Drum Magazine

A type of firearms magazine that is cylindrical in shape, similar to a drum. Probably the most recognizable drum magazine is the magazine for a Thompson carbine rifle, also known as the Tommy Gun.

Jacket

A metal, usually copper, wrapped around a lead core to form a bullet.

Slug

More correctly a "rifled slug" or "shotgun slug." An individual cylindrical projectile designed to be discharged from a shotgun. The term is often incorrectly used to mean a Bullet.