Letter O

The Definition of Obturation

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Obturation

The process of a bullet expanding under pressure to fit the bore of the firearm, or a cartridge case expanding under pressure to seal the chamber.


19 Other Firearms Definitions You Need To Know


Toplever

A lever on a break-open gun mounted to the top of the receiver which, when pushed with the thumb (normally) to the right, operates (usually) a Scott Spindle, which in turn withdraws (usually) a Purdey Underbolt from the bites in the lumps of the barrels, allowing them to hinge downwards and the gun to open.

Hand

In any mechanism, a small lever that engages a notch to actuate movement in one direction only. Specifically, a small spring-loaded lever attached to the hammer of a revolver which actuates the cylinder to advance one increment and move the next chamber into battery as the hammer is cocked.

Repeater

A type of firearm capable of discharging multiple individual shots in sequence, fed from a magazine, via the operation a lever, bolt, slide or some other form of manual operation.

Hang Fire

An unexpected delay between the triggering of a firearm and the ignition of the propellant. This failure was common in firearm actions that relied on open primer pans, due to the poor or inconsistent quality of the powder. Modern weapons are susceptible, particularly if the ammunition has been stored in an environment outside of the design specifications. Reloaded ammunition may also be the cause if not reloaded properly

Bull Barrel

Bull barrels are barrels that are not tapered at all. These very heavy barrels, designed for extreme accuracy, are usually seen on target rifles.

Nipple

A small metal tube extending through the breech of a percussion firearm through which the flame passes from the percussion cap to fire the powder charge.

Die

A piece of tooling used to form a sequence of uniform parts through the use of heat and/or pressure; especially, in firearms terminology used to form brass cartridge cases accurately to their correct size for reloading.

Bore Snake

A bore snake is a tool used to clean the inside (bore) of the barrel of a gun. It resembles a short section of rope with a smaller, weighted cord attached to one end to help feed the bore snake through the barrel. A bore snake often has one or more integrated brushes to help clean the barrel, and may also be used to apply lubricant. It is an alternative to using a cleaning rod and patches to clean the barrel of a gun. Bore snakes are made in different sizes for different calibers and gauges of guns.

Trigger Safety

An external, passive safety which can be found on the face of some trigger designs (most notably found on Glock firearms). It is intended to prevent the trigger from being pulled by objects which find their way into the trigger guard area.

OTM

Abbreviation for Open Tip Match.

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.

Hook

A concave, semi-cylindrical surface cut into the forward lump of a barrel set of a break-open firearm which revolves about the hinge-pin when the gun is opened.

Cast Off

An offset of a gun stock to the right, so that the line of sight aligns comfortably with the right eye while the butt of the stock rests comfortably on the right shoulder. Almost all right-handed shooters benefit from a little castoff and most custom built guns are made this way. The only question is how much. The castoff of a gun is about right when, with the gun comfortably mounted, the front bead lines up with the center of the standing breech.
A stock offset to the left, for shooting from the left shoulder is said to be

Optical Sight

Usually a telescopic firearm sight.

Grip

The portion of the stock (on a rifle) or frame (on a pistol) gripped by the trigger hand.

Snub-Nose

Slang word for short barreled revolver.

Six Gun

A slang term for a revolver that holds siz rounds. Usually referring to cowboy style revolvers.

Gun

A firearm.

Handgun

Synonymous with pistol. A small, short-barreled firearm designed to be fired while held in one or both hands, possibly small enough to be concealed on the person, rather than while braced against the shoulder. The term includes antique dueling pistols, modern single-shot, semi-automatic pistols and revolvers.