The physical mechanism that manipulates cartridges and/or seals the breech. The term refers to the method in which cartridges are loaded, locked, and extracted from the mechanism. Actions are generally categorized by the type of mechanism used. A firearm action is technically not present on muzzleloaders as all loading is done by hand. The mechanism that fires a muzzle-loader is called the lock.
Gunpowder and artillery. Since the design of the cartridge, the meaning has been transferred to the assembly of a projectile and its propellant in a single package.
barrel
A tube, usually metal, through which a controlled explosion or rapid expansion of gases are released to propel a projectile out of the end at high velocity.
A support device that is similar to a tripod or monopod, but with two legs. On firearms, bipods are commonly used on rifles to provide a forward rest and reduce motion. The bipod permits the operator to rest the weapon on the ground, a low wall, or other object, reducing operator fatigue and permitting increased accuracy.
A passivation process in which steel is partially protected against rust, and is named after the blue-black appearance of the resulting protective finish. True gunbluing is an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite (Fe3O4), the black oxide of iron, which occupies the same volume as metallic iron. Bluing is most commonly used by gun manufacturers, gunsmiths and gun owners to improve the cosmetic appearance of, and provide a measure of corrosion resistance to, their firearms.
A type of firearm action in which the firearm’s bolt is operated manually by the opening and closing of the breech (barrel) with a small handle. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and finally a new round/shell (if available) is placed into the breech and the bolt closed.
Crude adjustments made to an optical firearm sight, or iron sights, to align the firearm barrel and sights. This method is usually used to pre-align the sights, which makes zeroing (zero drop at XX distance) much faster.
a firearm configurations in which both the action and magazine are located behind the trigger.
the internal diameter of a firearm’s barrel or a cartridge’s bullet, usually expressed in millimeters or hundredths of an inch; in measuring rifledbarrels this may be measured across the lands (such as .303 British) or grooves (such as .308 Winchester) or; a specific cartridge for which a firearm is chambered, such as .44 Magnum. In artillery, the length of the barrel expressed in terms of the internal diameter.
a cartridge in which the primer is located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component. The centerfire cartridge has replaced the rimfire in all but the smallest cartridge sizes. Except for low-powered .22 and .17 caliber cartridges, and a handful of antiques, all modern pistol, rifle, and shotgun ammunition are centerfire.
the portion of the barrel or firing cylinder in which the cartridge is inserted prior to being fired. Rifles and pistols generally have a single chamber in their barrels, while revolvers have multiple chambers in their cylinders and no chamber in their barrel.
dry fire
the practice of “firing” a firearm without ammunition. That is, to pull the trigger and allow the hammer or striker to drop on an empty chamber.
For optics such as binoculars or a rifle scope, eye relief is the distance from the eyepiece to the viewer’s eye that matches the eyepiece exit pupil to the eye’s entrance pupil. Short eye relief requires the observer to press their eye close to the eyepiece in order to see an un-vignetted image. For a shooter, eye relief is an important safety consideration. An optic with too short an eye relief can cut skin at the contact point between the optic and the shooter’s eyebrow due to recoil.
A part in a firearm that serves to remove brass cases of fired ammunition after the ammunition has been fired. When the gun’s action cycles, the extractor lifts or removes the spent brass casing from the firing chamber.
The accumulation of unwanted material on solid surfaces. The fouling material can consist of either powder, lubrication residue, or bullet material such as lead or copper.
is a unit of measurement of mass that is based upon the mass of a single seed of a typical cereal. Used in firearms to denote the amount of powder in a cartridge or the weight of a bullet. Traditionally it was based on the weight of a grain of wheat or barley, but since 1958, the grain (gr) measure has been redefined using the International System of Units as precisely 64.79891 mg.[18][19] There are 7,000 grains per avoirdupois pound in the Imperial and U.S. customary units.
hammer bite
The action of an external hammer pinching or poking the web of the operator’s shooting hand between the thumb and fore-finger when the gun is fired. Some handguns prone to this are the M1911 pistol and the Browning Hi-Power.[20]
An unexpected delay between the triggering of a firearm and the ignition of the propellant. This failure was common in firearm actions that relied on open primer pans, due to the poor or inconsistent quality of the powder. Modern weapons are susceptible, particularly if the ammunition has been stored in an environment outside of the design specifications.
The function of the hammer is to strike the firing pin in a firearm, which in turn detonates the impact-sensitive cartridge primer. The hammer of a firearm was given its name for both resemblance and functional similarity to the common tool.
A headstamp is the markings on the bottom of a cartridge case designed for a firearm. It usually tells who manufactured the case. If it is a civilian case it often also tells the caliber, if it is military, the year of manufacture is often added.
are a system of aligned markers used to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of opticsas in a scope. Iron sights are typically composed of two component sights, formed by metal blades: a rear sight mounted perpendicular to the line of sight and consisting of some form of notch (open sight) or aperture (closed sight); and a front sight that is a post, bead, or ring.
A metal, usually copper, wrapped around a lead core to form a bullet.
length of pull
The distance between the trigger and the butt end of the stock of a rifle or shotgun.
A magazine is an ammunition storage and feeding device within or attached to a repeating firearm. Magazines may be integral to the firearm (fixed) or removable (detachable). The magazine functions by moving the cartridges stored in the magazine into a position where they may be loaded into the chamber by the action of the firearm.
The part of a firearm at the end of the barrel from which the projectile exits.
devices that are fitted to the muzzle of a firearm to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire.
The status of a weapon before the action has returned to the normal firing position. The term originates from artillery, referring to a gun that fires before it has been pulled back into its firing position in a gun battery. In firearms where there is an automatic loading mechanism, a condition in which a live round is at least partially in the firing chamber and capable of being fired, but is not properly secured by the usual mechanism of that particular weapon can occur.
a bracket used on some firearms to provide a standardized mounting platform.
Informal target shooting done at non-traditional targets such as tin cans, glass bottles, and balloons filled with water.[25]
A rifle or shotgun in which the handgrip can be pumped back and forth to eject a spent round of ammunition and to chamber a fresh one. It is much faster than a bolt-action and somewhat faster than a lever-action, as it does not require that the shooter remove their trigger hand during reloading. In rifles, this action is also commonly called a slide action.
The backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile, according to Newton’s third law. (often called kickback or simply kick)
Recoil operation is an operating mechanism used in locked-breech, autoloading firearms. As the name implies, these actions use the force of recoil to provide energy to cycle the action.
reflex sight
A generally non-magnifying optical device that has an optically collimated reticle, allowing the user to look through a partially reflecting glass element and see a parallax free cross hair or other projected aiming point superimposed on the field of view.[26] Invented in 1900 but not generally used on firearms until reliably illuminated versions were invented in the late 1970s (usually referred to by the abbreviation “reflex sight”).
a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing.
Helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis. This spin serves to gyroscopically stabilize the projectile, improving its aerodynamic stability and accuracy.
A type of firearm cartridge that used a firing pin to strike the base’s rim, instead of striking the primer cap at the center of the base of the cartridge to ignite it (as in a centerfire cartridge). The rim of the rimfire cartridge is essentially an extended and widened percussion cap that contains the priming compound, while the cartridge case itself contains the propellant powder and the projectile (bullet).
a premature, unintended discharge of a firearm that occurs as a round is being loaded into the chamber.
slide bite
A phenomenon often grouped with hammer bite—in this case the web of the shooting hand is cut or abraded by the rearward motion of the semi-automatic pistol’s slide, not by the gun’s hammer. This most often occurs with small pistols like the Walther PPK and Walther TPH that have an abbreviated grip tang. This problem is exacerbated by the sharp machining found on many firearms.
speedloader
A device used for loading a firearm or firearm magazine with loose ammunition very quickly. Generally, speedloaders are used for loading all chambers of a revolver simultaneously, although speedloaders of different designs are also used for the loading of fixed tubular magazines of shotguns and rifles, or the loading of box or drum magazines. Revolver speedloaders are used for revolvers having either swing-out cylinders or top-break cylinders.
also known as squib round, pop and no kick, or just squib: A firearms malfunction in which a fired projectile does not have enough force behind it to exit the barrel, and thus becomes stuck. Squib loads make the firearm unsafe to shoot, unless the projectile can be removed.
A mechanism that actuates the firing sequence of a firearm. Triggers almost universally consist of levers or buttons actuated by the index finger.
A small-caliber firearm or high-powered air gun primarily used for varmint hunting — killing non-native or non-game animals such as rats, house sparrows, starling, crows, ground squirrels, gophers, jackrabbits, marmots, groundhogs, porcupine, opossum, coyote, skunks, weasels,[30] or feral cats, dogs, goats, pigs and other animals considered a nuisance vermin destructive to native or domestic plants and animals.[31]
A custom cartridge for which ammunition and firearms are not mass-produced. These cartridges are often created to optimize a certain performance characteristic (such as the power, size or efficiency) of an existing commercial cartridge
The heading of a bullet, used in external ballistics that refers to how the Magnus effect causes bullets to move out of a straight line based on their spin.
zeroing
The act of setting up a telescopic or other sighting system so that the point of impact of a bullet matches the sights at a specified distance.