Second Amendment Armory Dictionary

Welcome to the Second Amendment Armory's dictionary. You can use this page to find the definition of words or abbreviations related to firearms. You can search the dictionary by entering a word, partial word, a word or combinations of words. Or, you can view all the words in the dictionary realted to a specificc letter. If you have suggestions for new terms, abbreviations, or deifnitions, please contact us at questions@saarmory.com.

Use the buttons to view all of the definitions of the words in the dictionary that start with that letter.

ACP

Automatic Colt Pistol. Colt's proprietary designation for a type of rimless cartridge design, such as .45 ACP.

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Action

The receiver of a gun containing the breech-locking and firing mechanism. The serialized part of the firearm.

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Action

Action is the term for the operating mechanism of a gun. It refers to the combination of moving parts that allow a shooter to load fire and unload a gun.

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Adjustable Sights

Sights that allow vertical (elevation) and horizontal (windage) adjustments.

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AE or Automatic Ejectors

Fittings inset into the breech end of barrels of a break-open gun that kick out fired shells, while only raising unfired shells enough to be removed by hand.

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ANIB

As new in original box. Perhaps fired, but in virtually new condition.

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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.

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Aperture

The hole in a rear peep sight through wich the shooter looks at the front sight and target.

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Aperture Sight

Peep Sight

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APUN

Action Patent Use Number. Under patent law during the period of greatest creativity in the British firearms trade (circa 1860 - 1910) gunmakers typically numbered each patented component with its own number of use of the patent (not the number of the patent itself as registered with the patent office as in the USA)---irrespective of the serial number of the firearm.

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Autoloading

An action of semi-automatic or self-loading operations.

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Automatic [Action]

A type of firearm which, utilizing some of the recoil or some of the expanding-gas energy from the firing cartridge, cycles the action to eject the spent shell, to chamber a fresh one from a magazine, to cock the mainspring and to fire again. Such a firearm will fire continuously as long as the trigger is held back, until the magazine is empty. A machine gun. A firearm activated as above, but which shoots only one bullet with each separate pull of the trigger, while often erroneously referred to as "automatic" is more properly termed Semi-Automatic.

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Automatic Safety

A safety catch on a break-open gun that resets to the "safe" position each time the gun is opened, usually via a limb attached to the toplever spindle.

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