The Definition of 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
A method of building a pair of barrels where the entire breech end of both barrels and the lumps together are machined
from one solid piece of steel. The barrel tubes are then fitted separately into this monoblock and the ribs attached.
Often identifiable by a distinctive ring around the barrels about three inches in front of the breech end.
The favored jointing method of the Beretta company. An incorrect euphemism for sleeved barrels.
A strap, usually of leather or sturdy webbing, fitted to the fore and aft (usually) of a rifle as an aid to carrying over the shoulder and as an aid to holding the rifle steadily while aiming.
A unit of adjustment for a sight.
The open end of the barrel from which the projectile exits.
An action type that when the trigger is pulled, the only thing the trigger does is drop the hammer (or striker).
This applies to both revolvers, semi-automatic and automatic guns.
On a single action revolver, the gun must be manually cocked before it can be fired.
With semi-automatic and automatic guns that are single action, the only thing the trigger does is drop the hammer, striker or firing pin onto the cartridge.
Then the firearm is cocked again when from the recoil of the fired round.
A firearm that the gun is cocked and the hammer drops when the trigger is pulled is a double action gun.
The distance, or clearance, between the base of a chambered cartridge and the breech face (or bolt face) of a firearm.
This is a critical dimension, particularly in high powered rifles. If there is too little headspace, the bolt will not close.
If there is too much headspace the cartridge will not be properly supported in the chamber and the cartridge will expand upon
firing and may rupture, blasting high-pressure gas into the action and possibly into the body of the shooter.
Headspace should be .003" - .006" in a centerfire rifle. It can be checked with a set of "Go and No-Go"
gauges specific to the calibre in question. (See below.) With a standard cartridge, the headspace is
registered by the shoulder, with a belted cartridge, the headspace is registered by the forward edge of the belt.
The entire process of moving the trigger from its forward-most position to its rearward-most position, causing the hammer to fall and the shot to fire.
By convention, powerfully loaded shotgun cartridges for hunting are generally manufactured with relatively longer brass end-caps than lower
powered cartridges intended for target shooting. While different-sized brass bases are of virtually no consequence to the strength of the
shell in relation to the steel breech of the gun itself, they do help the shooter identify the relative power of cartridges at a glance.
Any piece that projects from a firearm for the purpose of attaching something to it.
For example barrel lugs are used to attach a break-action shotgun barrel to the action itself.
If the firearm is a revolver, the term may also refer to a protrusion under the barrel that adds weight,
thereby stabilizing the gun during aiming, mitigating recoil, and reducing muzzle flip. A full lug extends all the way to the muzzle,
while a half lug extends only partially down the barrel. On a swing-out-cylinder revolver, the lug is slotted to accommodate the ejector rod.
A semi-automatic firearm malfunction in which the slide passes entirely over the fresh round, failing to pick it up to insert into the chamber as the slide returns to battery.
Most firearms do not have literal batteries. But a firearm is said to be in battery when the breech is fully closed and locked,
ready to fire. When the breech is open or unlocked, the gun is out of battery and no attempt should be made to fire it.
A semi-automatic is out of battery when the slide fails to come all the way forward again after the gun has fired, making it
dangerous or impossible to fire the next round. This condition can be created by a misfeed, a dirty gun, weak springs,
the shooter's thumbs brushing against the slide, riding the slide, or any of several other causes.
A metal cup placed on the end of a lead bullet to protect the lead against the hot gases of the burning powder charge.
Used in some types of firearms ammunition when non-jacketed bullets are used in high pressure cartridges, to prevent the buildup of lead in the barrel and aid in accuracy.
An armor-piercing shell must withstand the shock of punching through armor plating. Shells designed for this purpose
have a greatly strengthened case with a specially hardened and shaped nose,
and a much smaller bursting charge.
The part of a revolver that holds cartridges in
separate chambers radially around a central hingepin. The cylinder revolves as
the handgun is cocked, , either to the left or to the right depending on the gun maker's design,
bringing each successive cartridge into position, and
locked into alignment with the barrel for firing.
Openings at the muzzle end of the gun through which some of the spent gases can escape.
Porting reduces perceived recoil and lessens muzzle rise but increases the noise and flash.
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."
More commonly known as WRF, it is a family of rimfire cartridges designed by Winchester Repeating Arms Company
Racking the slide incorrectly by allowing your hand to rest upon the slide as it moves forward during the loading procedure. Riding the slide is a common cause of misfeeds and other malfunctions.
The top of the butt-end of a gun stock.
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