Letter D

The Definition of Drift

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Drift

The departure of a bullet or shot charge from the normal line of flight. This can be caused by wind or the unbalanced spinning of the bullet.


19 Other Firearms Definitions You Need To Know


Headspace

The distance, or clearance, between the base of a chambered cartridge and the breech face (or bolt face) of a firearm. This is a critical dimension, particularly in high powered rifles. If there is too little headspace, the bolt will not close. If there is too much headspace the cartridge will not be properly supported in the chamber and the cartridge will expand upon firing and may rupture, blasting high-pressure gas into the action and possibly into the body of the shooter. Headspace should be .003" - .006" in a centerfire rifle. It can be checked with a set of "Go and No-Go" gauges specific to the calibre in question. (See below.) With a standard cartridge, the headspace is registered by the shoulder, with a belted cartridge, the headspace is registered by the forward edge of the belt.

Short Recoil

A semi-automatic pistol in which the barrel and breechblock are locked together for only a short distance of rearward recoil travel, at which point the two are uncoupled, the barrel is stopped and the breechblock continues rearward, extracting the spent casing from the chamber. Upon returning forward, the breechblock chambers a fresh round and forces the barrel back into its forward position. Most modern recoil operated semi-automatic pistols use short recoil.

Minute Of Angle

A 1/60th part of a degree, the unit of measure used in adjusting rifle sights. As it turns out conveniently, a minute of angle translates almost exactly to one inch at 100 yards (actually 1.047 inches), to two inches at 200 yards and three inches at 300 yards

Checkering

A regular pattern of fine grooves cut into the surface of a stock to aid in gripping a gun. Originally done for utility only, checkering has become an art form in itself; craftsmen adorning the borders with ribbons, fleur-de-lys, floral carving, etc. The amount of coverage, the precise regularity, and the number of lines per inch indicate the quality of the work. Too-fine checkering, however, defeats the purpose of the work altogether.

Bullet

The single projectile expelled from a gun. It is not the same as a cartridge, the cartridge is complete package, which includes the case, primer, powder, and bullet, which is called or a round. Bullets can be of many materials, shapes, weights and constructions such as solid lead, lead with a jacket of harder metal, round-nosed, flat-nosed, hollow-pointed, etc.

Submachine Gun

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

Open Frame

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

Ears

Slang for hearing protection. Applies to either muffs or plugs.

Rifle

A shoulder-fired long gun which has a rifled barrel.

Explosive

Any substance (TNT, etc.) that, through chemical reaction, detonates or violently changes to gas with accompanying heat and pressure.

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.

Half Cock

A middle position for an external hammer that effectively provides a safety function. With a firearm with non-rebounding hammers, when on half-cock, the firing pin will not rest on the firing-pin.

Limp Wristing

A floppy, limp wrist while shooting.

ACP

The abbreviation for Automatic Colt Pistol. It is commonly used to designate specific calibers, particularly those which were originally designed by John Moses Browning for the Colt Firearms Company which are a type of rimless pistol cartridge designed mainly for use in semi-automatic pistols. The most common ACP calibers are .25 ACP, .32 ACP, .380 ACP and .45 ACP.

Magazine Pouch

Commonly shortened to mag pouch, this is a device to hold extra magazines which fastens to the shooter's belt.

Timing

The proper adjustment of the various interrelated moving parts of a gun so that every operation works in proper sequence, such as that the two ejectors of a double gun kick out the spent cases at the same instant and with the same force.

Backstrap

The rearmost surface of the grip on a handgun. the term originated with old pistols. The grips surrounded the frame, making the rearmost of the frame appear as a strap.

Misfire

The condition of a cartridge not firing when an attempt to fire it is made. It can be caused by either a defective cartridge or a defective firearm. The term is frequently misused to indicate a Negligent Discharge of a firearm.

Kentucky Rifle

Usually referred to as a Kentucky Long Rifle or simply Longrifle, the Kentucky Rifle is a flintlock rifle with a long barrel and short, crooked stock. It is widely believed to be a largely unique development of American rifles that was uncommon in European rifles of the same period. The Kentucky Long Rifleis an early example of a firearm using rifling, (spiral grooves in the bore). This gave the projectile, commonly a round lead ball, a spiraling motion, increasing the stability of the trajectory. Rifled firearms saw their first major combat usage in the American colonies during the Seven Years war, and later the American Revolution in the eighteenth century.