Letter T

The Definition of Trigger Scale

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19 Other Firearms Definitions You Need To Know


Caliber

The diameter of the bore of a firearm measured as a fraction of an inch. Although such a measurement may be frequently stated in millimeters. It is correctly expressed as ".40 caliber" (note the decimal point) or as "10 millimeter" (without "caliber" or the leading decimal point). Caliber numbers when used to identify the size of the bullet a gun will file are usually followed by words or letters to create the complete name of the cartridge. These letters often represent a brand name or an abbreviation for the name of the company that first introduced the round.

Co-Witness Sighting

Co-Witness Sighting is the use of any iron sight mounted onto a rifle that is fitted with an optical sight as a primary sighting system. They come in two basic configurations, fixed or flip-up. The idea is that if you align your red dot and your iron sights you have a backup aiming system on the gun.

Parabellum

Latin word meaning "for war." It is actually the proper name of the semiautomatic pistol commonly known in the USA as the "Luger. Because of that pistol and the ammunition created for it, the common 9mm cartridge used nowadays is also known as 9mm Parabellum or 9mm Luger."

Breech

The rear end of the barrel into which the cartridge is inserted

Twilight Sight

A rifle front sight with a extra-large, folding bead. Typically, in addition to the normal fine bead (which allows for more precision) the larger bead, while at a cost of potential accuracy, is more readily acquired in marginal light. Also called a Gloaming sight

Double-Set Trigger

Usually only found on black powder muzzle loading rifles and pistols, pulling the rear (set) trigger converts the front (main) trigger to a light, hair trigger (too light and sensitive to be carried safely in the field). While the front trigger is always at the ready, if one has the time, using the set trigger feature may allow for a more accurate long-distance shot. Operates using its own miniature firing mechanism (sear, spring and hammer) when cocked, to multiply the force of a pull on the main trigger.

Bandolier

A pocketed belt for holding ammunition and cartridges. It was usually slung over the chest. Bandoliers are now rare because most military arms use magazines which are not well-suited to being stored in such a manner. They are, however, still commonly used with shotguns, as individual 12 gauge shells can easily be stored in traditionally designed bandoliers.

Velocity

The speed at which a projectile travels. Velocity is usually measured in feet per second or metres per second.

Annulus

A tiny circular recess at the base of a cartridge case surrounding the primer pocket. Recoil from fired cartridges invariably impress a discernable ring on the breech or bolt face of a firearm, providing some evidence of the amount of use it has seen.

Eye Dominance

Although we have two eyes for depth perception and for spare parts, there is a natural tendency for one eye (the master eye) to take precedence over the other, regardless of the relative visual acuity of each eye. It is a fortunate condition when the eye on the side of the shoulder where one is comfortable mounting a gun is also the dominant eye.
To test for eye dominance:

Pick out a small object several feet away. With both eyes open, center your right index finger vertically over the object. Close your right eye. If your finger appears to jump to the right, you are right eye dominant. Then open your right eye and close your left eye. If your finger remains in position in front of the object, you have confirmed your right eye dominance. Alternatively, if in the above test, upon closing your right eye your finger remains in position covering the object, you are left eye dominant. If you close your left eye instead and your finger appears to jump to the left you have confirmed your left eye dominance.
Eye dominance problems can be treated with
1. A severely-cast, crossover stock to bring the dominant eye in line with the gun's line of sight, 2. A patch over the dominant eye, or just a small piece of frosty Scotch tape on shooting glasses intercepting the dominant eye's line of sight, 3. Fully or partially closing the dominant eye, or 4. Learning to shoot from the dominant-eye shoulder.
While less convenient, methods that retain the use of both eyes better preserve the ability to perceive depth in three-dimensional space, a great benefit in wingshooting.

Windage

The setting on the sights used to accommodate the wind or adjust for horizontal (side-to-side) errors in the alignment of the sights with the bore of the firearm.

Trigger Guard

Usually a circular or oval band of metal, horn or plastic that goes around the trigger to provide both protection and safety in shooting circumstances. The shooter's finger should never be within the trigger guard unless the sights are on target and the shooter has made the decision to fire.

Fixed Ammunition

A complete cartridge of several obsolete types and of today's rimfire and center-fire versions

Four Rules

The four rules of firearms safety,were originally introduced in the early 1900's by various shooting education sources (with varying phrasing, but same implications), they apply every single time a firearm is handled in any way or for any reason. The NRA teaches the Three Rules of Safe Gun Handling.

Rule One: All guns are always loaded. (Treat all guns as if they are loaded, no matter what!)
Rule Two: Never point your firearm at anything you are not willing to destroy.
Rule Three: Never put your finger on the trigger unless your sights are on target (and you have made the decision to fire).
Rule Four: Be sure of your target and what is behind it.

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.

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.