Letter J

The Definition of Jacket

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Jacket

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


19 Other Firearms Definitions You Need To Know


Open Frame

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

LCI

Abbreviation for Loaded Chamber Indicator

Recoil Lug

A stout flange, invariably incorporated into the underside of the front receiver ring of a bolt action, and also frequently incorporated into the underside of the barrel of a heavily-recoiling rifle, which when properly bedded, transfers recoil to the stock.

Trajectory

The arc described by a projectile (or a load of shot) after it exits the muzzle of a firearm. Falling objects accelerate downwards at a rate of 32 feet per second, per second. The faster a projectile travels, the greater the distance it can cover in a given time before dropping too far. Hence, the higher the velocity of a bullet, the flatter the trajectory it will achieve.

Striker

In a handgun that does not have a hammer, the striker is a linear driven, spring loaded cylindrical part which strikes the primer of a chambered cartridge. The striker replaces both the hammer and firing pin found in hammer driven pistols.

Silencer

Improper term for a device that cuts down on the noise a firearm makes when it is shot. The correct term is suppressor. Silencers only exist in the movies.

Ejector

A spring-activated mechanism for the ejection of ammunition or and empty shell casing. On doubles, each barrel has a separate ejector.

Full Stock

A rifle or carbine with a one-piece stock extending to the muzzle. Sometimes called a Mannlicher stock, although such a term is confusing because Mannlicher Schoenauer rifles are built with both full and half stocks. Traditional in Europe for close-range woodland hunting, but not noted for extreme, long-range accuracy.

Belt Fed

A firearm, usually (but not always) a fully automatic rifle, that uses a ammunition on a belt rather than a magazine to store the rounds that will be loaded into the gun.

Limp Wristing

A floppy, limp wrist while shooting.

Rail Mount

Any type of accessory that can be attached to a firearm's rail.

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.

Rifle Bedding

A process of filling gaps between the action and the stock of a rifle with an epoxy based material.

Three Rules

The NRA teaches the Three Basic Rules of Safe Gun Handling. There are additional rules, but these are the three that if any two are followed, nobody will be hurt. However, obviously, all three should always be followed.

Rule One: ALWAYS keep the gun pointed in a safe direction.
Rule Two: ALWAYS keep your finger off the trigger until ready to shoot.
Rule Three: ALWAYS keep the gun unloaded until ready to use.
The NRA established these three rules in 1871. They were created to be easy to understand and remember, ensuring the highest possible level of firearm safety.
See also The Four Rules

Trapdoor

As in Trapdoor buttplate or Trapdoor Pistol Grip Cap, one of these articles of furniture including a hinged plate, covering a small compartment below in which may be stored several extra cartridges, sight bits, extra springs or pins, cleaning rod, etc.

Shell Casing

A hollow, piece of metal (or plastic in the case of a shotgun shell) that is closed on one end except for a small hole which holds a primer. The open end holds the bullet. The hollow portion holds the powder. Together the assembled unit is called a cartridge.

Yaw

The heading of a bullet, used in external ballistics that refers to how the Magnus effect causes bullets to move out of a straight line based on their spin.

Matchlock

A black powder muzzleloading firearm action which relies upon a serpentine or S-shaped piece of metal to hold a smoldering match. By pressing the lower end of the serpentine, the upper end holding the burning match contacts the priming powder in the pan.

Pre-Travel

Some triggers can be pulled slightly backwards before the shooter can feel any tension and before the hammer or striker begins to retract. Pre-travel is any movement of the trigger that begins before the trigger starts to engage.