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


FFL

Abbreviation for Federal Firearms [Dealer's] License.

Carbine

A rifle with a relatively short barrel.

Out of Battery

A semi-automatic is said to be out of battery when the slide fails to come all the way forward again after the gun has fired. This condition can be created by a misfeed, a dirty gun, weak springs, the shooter's thumbs brushing against the slide, riding the slide, or any of several other causes.

Handloading

The process of assembling cartridge case, bullet or shot, wads and primer to produce a complete cartridge with the use of hand tools in the interest of loading for firearms for which cartridges are not available, experimenting with loads to achieve better performance, or to save money. Not to be attempted without knowledgeable instruction and careful study of the process.

Reactive Targets

Targets that do something when you hit them, such as fall over, burst, send up smoke, or make a noise.

OTM

Abbreviation for Open Tip Match.

Musketoon

A musket shortened for cavalry use.

Gas Port

A small hole in the barrel of a gas-operated firearm through which expanding gases escape to power the autoloading system.

Inertia Firing Pin

A firing pin which moves freely forward and backward in the breechblock.

Necking Up

Expanding the neck of an existing cartridge to make it use a bullet of a different caliber. A typical process used in the creation of wildcat cartridges.

AD

Abbreviation for Accidental Discharge

Primer Ring

Refers to a visible dark ring created by the primers in centerfire ammunition around the firing pin hole in the frame after much use.

Light Double Action

A double-action semi-automatic firearm which is designed to have a much lighter trigger pull than is usual for a double action.

Quadrail

Sometimes spelled Quad Rail. First conceived and sold by Knights Armament Company in the mid 90s when Reed Knight saw soldiers duct taping flashlights to their handguards in news footage of Panama, the quad rail has become almost a standard item found on most military rifles. Quad rails allow easy attachment of accessories which aid tactical shooters, such as lights, infrared lasers, foregrips, sling attachment points, and secondary sighting systems. However, nowadays, any full length forearms on an AR, with or without rails may also be refered to as a Quadrail.

Knurled Surface

A metal surface which contains a pattern of ridges or beads.

Cold Clean Bore

The first shot from a rifle that has been cleaned, and not fired recently may go to a different point of impact, for the same point of aim than a rifle that has been fired recently. This first shot is referred to as a shot from a cold, clean, bore.

Flinch

To jerk a firearm off target inadvertently in the instant of firing in timid anticipation of recoil. Commonly caused by learning to shoot with a gun more powerful then they are ready for.

BUG

Abbreviation for 'Back Up Gun'

Recoil Operation

Recoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action.