Letter S

The Definition of Sectional Density

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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.


19 Other Firearms Definitions You Need To Know


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

Black Powder

Also known as Gun Powder. A mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing a volume of hot gas made up of carbon dioxide, water, and nitrogen, and a solid residue of potassium sulfide. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. Modern firearms do not use the traditional black powder described here, but instead use smokeless powder.

Ejection Rod

The sliding metal dowel located at the muzzle end of a revolver cylinder. After firing, the shooter opens the cylinder and depresses the front end of the ejection rod, which forces the empty cases out of the cylinder.

Limp Wristing

A floppy, limp wrist while shooting.

SMLE

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

C&R

Abbreviation for Curio and Relic

Bolt Action

A type of firearm action in which the guns's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and finally a new round/shell (if available) is placed into the breech and the bolt closed.

Grooves

The cut-away, concave portions of the rifling inside the barrel of a firearm discharging a single projectile.In other words, the lower portion of rifling.

Combination Gun

A shoulder-held firearm that has two barrels; one rifle barrel and one shotgun barrel. Most combination guns are of an over/under design (abbreviated as O/U), in which the two barrels are stacked vertically on top of each other, but some combination guns are of a side-by-side design (abbreviated as SxS), in which the two barrels sit beside each other.

Lock

The firing mechanism of a a muzzle-loading weapon. In breech-loading firearms, the lock is the firing mechanism and breech-sealing assembly.

Load

A charge of powder, a projectile or a cartridge. Also, to prepare a gun for firing by inserting ammunition into it.

Reset Point

The point of the trigger's return at which the gun's internal mechanisms are ready to fire another round.

M1911

The official US military designation for the Colt .45 semiautomatic pistol adopted by the US in 1911. The gun was designed by John Moses Browning, and produced by Colt. During trials, the Browning-Colt design beat out several competing designs, including one from Savage and a .45 caliber version of the German Parabellum ("Luger"). The M1911 saw its first combat in the Philippines and then in World War I. Early use showed that it could be improved and in 1921 the M1911A1 was introduced, which featured a few changes like a reocontoured frame, shorter trigger, and a rounded backstrap. The M1911A1 remained the standard US military handgun until it was replaced in the 1980's by the Beretta M9. However, it remains very popular with civilian shooters in the US, and has been modified extensively to update it to conform to more modern theories of handgun usage.

Doglock

The lock that preceded the 'true' flintlock in both rifles and pistols in the 17th century. Commonly used throughout Europe in the 1600s, it gained popular favor in the British and Dutch military. A doglock carbine was the principal weapon of the harquebusier, the most numerous type of cavalry in the armies of Thirty Years War and the English Civil War era.

Sling

A long strip of leather, plastic, or nylon which is fastened at the fore and rear of the gun for the easy carry of long guns.

SP

Abbreviation for soft point

Lands

In the rifling of a bore, the uncut portions of the barrel's inner surface left after the rifling grooves have been cut into the metal. In other words, the raised portion of rifling.

Interrupted Thread

A screw with about half of its threading removed in longitudinal sections. Often used at the breech end of a takedown firearm's barrel. When the barrel's interrupted female threads are inserted into the receiver's complementary interrupted male threads, only a partial rotation is necessary for assembly rather than many full turns.

Straddle Floorplate

A hinged plate covering the bottom of a rifle magazine and extending rearward on either side of the triggerguard. This design allows it to be more securely fastened for one more imperceptible step towards total reliability.

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