Letter O

The Definition of Open Frame

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Open Frame

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


19 Other Firearms Definitions You Need To Know


MOA

Abbreviation for Minute Of Angle

Keyhole

The tendency of a bullet to tip in flight and hit a target sideways, leaving a distinctly oblong hole. This destabilization of the spinning bullet in flight is typically caused by a bullet weight inappropriate for the rate of twist of the rifled barrel, an out-of-balance bullet or its having nicked an impediment such as a blade of grass, in flight.

Sawed-Off Shotgun

Common term for federally restricted "short-barreled shotgun (rifle)" as with a conventional shotgun with barrel less than 18" (rifle less than 16") or overall length less than 26.

Shotshell

Same as a Shotgun Shell.

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.

Skeet

A shotgun shooting sport in which the competitors attempt to break aerial targets directed toward them or crossing in front of them from different angles and elevations. It is an Olympic shooting sport.

Express Sights

"V" shaped rear leaf sights mounted to a rifle barrel on a block or on a quarter-rib, sometimes solid standing, sometimes folding, and often mounted in a row of similar leaves, each of a slightly different height, marked with the range for which each is regulated

Scope Blocks

A pair of small dovetailed steel bases, screwed usually one to the barrel and one to the front receiver ring of a rifle, to accept mounts for target scopes such as the Unertl where the scope is allowed to move forward in the rings under the recoil of the rifle and which typically carry the windage and elevation adjustments in the mount.

Primer

A small metal cup that contains a tiny explosive charge that is sensitive to impact. A primer is placed in the base of a shell casing to ignite the powder of the completed cartridge. It is detonated by the striking of a firing pin in the firearm.

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.

Scope Blocks

A pair of small dovetailed steel bases, screwed usually one to the barrel and one to the front receiver ring of a rifle, to accept mounts for target scopes such as the Unertl where the scope is allowed to move forward in the rings under the recoil of the rifle and which typically carry the windage and elevation adjustments in the mount.

Antique Firearm

Defined according to Section 921 (a) (16), Title 18, U.S.C. as:

A. any firearm (including any firearm with matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured in or before 1898; and
B. any replica of any firearm described in subparagraph (A) if such replica (i) is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition, or (ii) uses rimfire or conventional centerfire fixed ammunition which is no longer manufactured in the United States and which is not readily available in the ordinary channels of commercial trade.

SxS

Abbreviation for Side-By-Side.

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.

Flat Nose

A bullet shape with a flat nose rather than a rounded one.

Trigger Jerk

Yanking the trigger back abruptly, thus pulling the muzzle of the gun downward at the moment the shot fires.

WC

Abbreviation for wadcutter.

Howdah Pistol

Normally, a break-open, double-barrel, side-by-side pistol of large calibre, used by a maharaja when hunting tiger on the back of his elephant (in the howdah, the basket compartment in which he sits). The howdah pistol is the weapon of last resort in case the tiger tries to join him in the howdah.

Semi-Wadcutter

A bullet design featuring a conical extended nose, with a flat point, and a sharp edged shoulder that serves to cut a full diameter hole in the target. This design also may be found with a hollow point to facilitate expansion. A modified wadcutter bullet design with slightly sloping edges, designed to load smoothly in a semi-automatic pistol.