Letter E

The Definition of Eye Relief

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Eye Relief

The distance that equates the exit pupil size of a rifle scope's ocular lens to the entrance pupil of the user, in order to achieve the largest, unvignetted view. This distance must be sufficient to ensure that the ocular rim of the scope does not lacerate the shooter's eyebrow upon recoil. And, the scope should be positioned so that eye relief is suitable when the rifle is comfortably mounted.


19 Other Firearms Definitions You Need To Know


Loading Gate

The hinged cover over the opening through which cartridges are inserted into the magazine.

Deringer

The original small single-shot or multi-barreled pocket pistol designed and manufactured by Henry Deringer of Philadelphia. Derringers (spelled with two Rs) are called that because of the original desinger and anmufactuturer of that type of gun, Henry Deringer. To get around copyright infringment other designers and manufacturers spell the name with two Rs. However guns designed and built by Deringer are spelled with only one R

Pigeon Gun

A double-barrel shotgun, with relatively tight choke boring and a relatively high-combed stock used for shooting live pigeons (euphemistically known as flyers) which normally rise when released. To better absorb recoil, a pigeon gun is normally heavier than a field gun as one shoots heavy loads and walks only a little. Because of the inevitable expense of this shooting discipline, pigeon guns are often built to a high standard of quality and reliability in deluxe grades with highly figured walnut stocks and fine engraving.

Matchlock

An early system of ignition for muzzle-loading firearms where a priming charge is loaded into a flashpan with a separate, manually-operated cover. To fire, the cover is opened and then a slowly smoldering wick, held in the nose of the curved arm, is lowered by means of a lever (precursor to a trigger) to ignite a priming charge which then ignites the main propellant charge inside the barrel.

Short Trigger

A trigger that doesn't have to travel very far before it reaches the break. In a 1911 semi-auto pistol, a short trigger is a different part than a long trigger, and (in addition to providing less motion) it features a shorter reach which may be of benefit to a small-handed shooter.

Sabot

An oversized, lightweight housing that allows a sub-calibre projectile to be fired in a larger-diameter bore, usually in the interest of increased velocity. The sabot falls away from the actual projectile upon exiting the muzzle. For example, a hunter could use his .30-30 deer rifle to shoot small game with .22 centerfire bullets.

Casing

Also known as a Case. The envelope (container) of a cartridge. For rifles and handguns it is usually of brass or other metal; for shotguns it is usually of paper or plastic with a metal head and is more often called a "shell."

Long Recoil

A semi-automatic pistol in which the barrel and breechblock are locked together for the full distance of rearward recoil travel, after which the barrel returns forward, while the breechblock is held back. After the barrel has fully returned, the breechblock is released to fly forward, chambering a fresh round in the process.

Loaded Chamber Indicator

A mechanical device that protrudes from the gun when a round is in position ready to be fired, giving a visual and tactile indication that the gun is loaded.

Brick

A box of ammunition roughly equal in size and weight to a brick. Most often used to describe a 500-round container of .22 Long Rifle ammunition.

Double Feed

A malfunction in which the spent case fails to eject from a semi-automatic firearm and blocks the chamber. As the fresh round is brought forward it cannot enter the chamber. It is cleared by stripping the magazine from the gun, racking the slide several times to eject the spent case, and then reloading.

Neck

The forward portion of a bottlenecked cartridge case. Also the portion of a rifle chamber in which the neck of the cartridge case rests.

Pellet Gun

An air gun that shoots a skirted pellet.

Weapon

Anything that can be used in an offensive attack or in defense of an offensive attack. Guns are not necessarily weapons.
A gun can be used as a weapon, but so can a pencil, fist, car, a wad of paper or any other object used to attack or retaliate against an offensive attack. Even words can be used as a weapon.
Guns and other objects should be always called what they are; gun, rifle, pistol, pencil, knife, tomato or whatever they are. They should never be referred to as a weapon, EVER.
Some examples of the proper usage for the word "weapon" would be:
"One weapon used in the attack against the left flank was dirt clods".
"The marshmallow gun was the weapon of choice used in the accounting vs marketing skirmishes."
"The liberal leftists use words and restrictive controlling laws as weapons against the freedom of the people."

Gunpowder

Also called black powder, gunpowder is 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. The term gunpowder also refers broadly to any propellant powder. Modern firearms do not use the traditional gunpowder (black powder) described here, but instead use smokeless powder.

Improvised Firearm

A firearm manufactured by someone who is not a regular maker of firearms.

Sight Radius

The distance between the rear sight and the front sight. As a longer lever provides greater mechanical advantage, the greater the distance between the two sights, the more inherently accurate they will be.

ACP

The abbreviation for Automatic Colt Pistol. It is commonly used to designate specific calibers, particularly those which were originally designed by John Moses Browning for the Colt Firearms Company which are a type of rimless pistol cartridge designed mainly for use in semi-automatic pistols. The most common ACP calibers are .25 ACP, .32 ACP, .380 ACP and .45 ACP.

AR

Contrary to some people's belief, AR does NOT stand for Assault Rifle. The designation AR stands for the original designing company ArmaLite.
An AR is a firearm platform originally designed by ArmaLite and built by Colt, an AR is a lightweight, intermediate cartridge magazine-fed, air-cooled rifle with a rotating lock bolt, actuated by direct impingement gas operation or long/short stroke piston operation. It has been produced in many different versions, including numerous semi-automatic and selective fire variants. It is manufactured with extensive use of aluminum alloys and synthetic materials. Types of ARs include AR-15, AR-10 and AR-7.