TopGunReview’s Gun Glossary is designed to help you navigate the complex world of firearm vocabulary. It doesn’t matter if you are an expert or novice this gun glossary will give you clear definitions to the words you are looking for. If we are missing a firearm term you are looking for please contact us and we will find the meaning for you.
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ACP stands for Automatic Colt Pistol. It represents multiple pistol cartridge designs by John Moses Browning for both Colt Firearms and Fabrique Nationale de Herstal.
Action is the mechanism within a firearm that locks, removes, then reloads a new cartridge for firing.
See also: Bolt-Action, Break-Action, Double Action, Single Action
Adjustable Stock is a stock that can be shortened or lengthened to fit the shooter.
See also: Stock
Ammo short for Ammunition
Ammunition are the components that are need to fire a case or shell. The parts include a primer (makes a spark), propellant (gunpowder), and the projectile (ball, bullet, or even pellet). Ammunition comes in all sizes but remember it has to match the firearm.
See also: Cartridge, Rounds
AR-15 is the commonly known semi-automatic rifle. The AR acronym comes from manufacturer Armalite not from “Assault Rifle”.
Assault Rifle by US Army definition, is a selective-fire rifle chambered for a cartridge of intermediate power. If applied to any semi-automatic firearm regardless of its cosmetic similarity to a true assault rifle, the term is incorrect.
Automatic is a firearm type that is designed to continually fire cartridges by holding down the trigger. This system works as long as the trigger is pressed and cartridges last. Examples: machine guns, submachine guns, etc.
Ball is a spherical projectile, now generally a fully jacketed bullet of cylindrical profile with round or pointed nose.
Ballistics is the science of projectiles and firearms. It can be categorized in three phases. Internal ballistics focuses on what happens inside the firearm during discharge. External ballistics looks at the projectiles flight path. Lastly Terminal ballistics deals with the impact of the projectile with target.
Barrel is the tube, usually metal, which the bullet or shot travels. The barrel manages the direction and velocity to the bullet.
Backstop is any material that will safely stop a projectile after hitting a target. The projectile should not penetrate anything past it.
Bipod is a two legged support for stabilizing the front end of a rifle while shooting.
Blackpowder is the earliest type of firearms propellant that has generally been replaced by smokeless powder except for use in muzzleloaders and older breechloading guns that demand its lower pressure levels.
Blank Cartridge is a round loaded with blackpowder or a special smokeless powder but lacking a projectile. Used mainly in starting races, theatrical productions, troop exercises and in training dogs.
Bolt is cylindrical shaft, controlled by an attached lever. It is used in Bolt-Action firearms to load and unload the gun.
Bolt-Action is a firearm type that is designed to insert and remove shells by opening and closing a metal cylinder shaped mechanism called a bolt.
Bore is the hollow portion of a barrel through which the bullet travels during it’s acceleration phase.
Brass is a slang term for an empty shell casing. Most shell casings are made of the metal alloy known as brass.
Break-Action is a firearm whose barrels are hinged, and rotate perpendicular to the bore axis to expose the breech and allow loading and unloading of ammunition.
Breech is the portion of the gun that contains the rear chamber portion of the barrel. The rearmost end of a barrel, closest to the shooter.
Bullet is the projectile expelled from a gun. It is not synonymous with cartridge. Bullets can be of many materials, shapes, weights and constructions such as solid lead, lead with a jacket of harder metal, round-nosed, flat-nosed, hollow-pointed, etc.
Bullpup is a firearm configuration in which both the action and magazine are located behind the trigger.
Caliber/Calibre is the diameter of the internal bore of a rifled-barreled firearm. In the US, usually expressed in hundreds of an inch; in Great Britain in thousandths; in Europe and elsewhere in millimeters.
Cartridge is a single, complete round of ammunition which includes the case, primer, powder, and bullet.
Case, Casing is 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.”
Center-Fire is a cartridge with its primer located in the center of the base of the case.
Chamber is the rear part of the barrel that is formed to accept the cartridge to be fired. A revolver employs a multi-chambered rotating cylinder separated from the stationary barrel.
Choke is a constriction at or near the muzzle of a shotgun barrel that affects shot spread.
Clip is the controversial name commonly used to describe a magazine which is an ammunition storage and feeding device 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.
Cock is to put tension on the mainspring of a gun in preparation for firing, such as by pulling back the external hammer, pulling back the slide of a pistol, or opening and closing the barrel(s) of a break-open gun. Some external hammers, and all internal hammers, may be cocked simply by pulling the trigger.
Cocked is the state of readiness of a firearm. The hammer (or similar mechanism if there is no hammer) only needs to be released by the trigger to cause the gun to fire.
Crosshairs is the basic form of telescopic sight reticle, having one fine vertical line and one fine horizontal line with which to establish the point of aim.
Cylinder is a rotating cartridge holder in a revolver. The cartridges are held in the chambers and the cylinder turns, either to the left or to the right depending on the gun maker’s design, as the hammer is cocked.
Decocker is on double-action semi-automatic firearms, a lever that mechanically lowers the hammer without firing the gun. In German: Handspanner.
Derringer is a small single-shot or multi-barrelled (rarely more than two) pocket pistol.
Double Action (DA) is a type of firearm that may be discharged either by manually cocking the weapon and then pulling the trigger or by using trigger action to both cock and fire the weapon. Originally used only for revolvers but now common in semi-autos as well, Now it commonly means a revolver or pistol on which a long trigger pull can both cock and release the hammer to fire the weapon. In a revolver this action also rotates the cylinder to the next chambered round.
Double Action/Single Action (DA/SA) is a type of firearm that is designed to operate in double action on the first shot, and in single action on the second and subsequent shots.
Double Action Only (DAO) is a type of firearm in which the firing mechanism cannot be cocked in a single-action stage. Firing always occurs as a double-action sequence where pulling the trigger both cocks and then fires the gun.
Double Barrel is a shotgun with two barrels either side by side or one over the other.
Dry Firing is the operation of a firearm without the use of ammunition, as a means of gaining familiarity and technique. Dry firing must be done very carefully with a verified unloaded gun.
Dud is a round of ammunition that does not fire.
Dummy Round is a round of ammunition that is completely inert, i.e., contains no primer, propellant, or explosive charge. It is used to check weapon function, and for crew training. Unlike a blank it contains no charge at all.
Ear Plugs are hearing protection that fits inside the ear canal.
Ears is slang for hearing protection, muffs or plugs. The use of specially designed ear muffs or plugs that reduce the intensity of the sound reaching the ears is of course recommended. Some of the guns are so loud that a single shot can can cause permanent damage to unprotected ears.
Earmuffs are hearing protection that completely covers both ears and is usually attached to a headband.
Ejector is a spring-activated mechanism for the ejection of ammunition or and empty shell casing. On doubles, each barrel has a separate ejector.
Ejection Port is the opening through which the empty, spent ammunition case is ejected from of a firearm.
Electronic Hearing Protection is over ear hearing protection that has internal electronics that amplify human voices while excluding all noises louder than a given decibel rating.
Explosive is any substance (TNT, etc.) that, through chemical reaction, detonates or violently changes to gas with accompanying heat and pressure.
Extractor is a device that withdraws or elevates a fired shell casing from the chamber as the breech mechanism (slide) is opened.
External Safety is a safety lever found on the outer surfaces of the firearm and accessible to the user.
Eye Dominance 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.
Eye Relief 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.
Eyes is slang for safety glasses or other protection for the eyes. All shooters and spotters are required to wear eye protection while shooting is in progress.
Factory Ammo is ammunition that has been assembled by a commercial vendor of ammunition and sold in retail stores. This is as opposed to Hand loads which have been assembled by individuals and are not typically sold.
Failure To Extract is a semi-automatic firearm malfunction in which the extractor fails to move the empty case out of the way as the slide travels back. A failure to extract often causes double-feed malfunction.
Failure To Feed is 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.
Failure To Fire is any malfunction that results in no shot fired when the trigger is pulled. Commonly caused by a failure to feed, bad ammunition or a broken firing pin.
FFL means Federal Firearms [Dealer’s] License. Under federal law, to ship a firearm, a selling dealer must have in his possession a copy of the receiving dealer’s license.
Firepower is a volume of fire delivered by a military unit. Incorrectly used by the media to mean the ability of a small arm to be discharged many times without reloading.
Firearm is a rifle, shotgun or handgun using gunpowder as a propellant. By federal definition, under the 1968 Gun Control Act. Air guns are not, by definition, firearms.
Firing Line is a line, either imaginary or marked, from which people shoot their firearms down range.
Firing Pin is a needle like metal part of a modern firearm that gives a vigorous strike to the primer initiating the firing of the cartridge.
Fixed Ammunition is a complete cartridge of several obsolete types and of today’s rimfire and center-fire versions.
Flash Hider/Flash Suppressor is a muzzle attachment intended to reduce visible muzzle flash caused by the burning propellant. Flash reducers lessen glare as seen by the shooter, but do not hide the flash from other observers to the front or side of the firearm.
Flat Point or Flat Nose is a bullet shape with a flat nose rather than a rounded one.
Flinch is when you jerk the gun downwards just before the shot fires. Commonly caused by learning to shoot with a gun more powerful then they are ready for.
Floated Barrel is a rifle barrel mounted firmly to the receiver (which, in turn, is mounted firmly to the stock) but not touching the forend. Done so that the stock will not adversely effect accuracy by impinging upon the natural free vibration of the barrel when the rifle is fired.
Folding Stock is a long gun stock that may be doubled over for conveniently compact storage.
Follow Through occurs when you hold the trigger to the rear after the shot has fired, until the sights are back on target, at which time the trigger is released.
Fouling is the gritty residue that cleaned out of the barrel and all areas of the firearm in order to clean it.
Fouling Shot is a shot fired in a clean rifle barrel to put the barrel into the normal slightly dirty state from which it is fired. Often, a rifle will shoot to a different point of aim with this shot as compared to the subsequent shots.
Four Rules are the four universal rules of firearms safety, which apply every single time a firearm is handled in any way or for any reason.
- Rule One: All guns are always loaded. (Treat them so!)
- 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.
Forend is the part of the stock forward of the action and located below the barrel or barrels. It is designed to give the shooter a place to hold the front end of the gun and protects the shooter’s hand from getting burned on the hot barrel.
Frame is the common part of a handgun to which the action, barrel and grip are connected.
Front Sight is the sight placed at the muzzle end of the barrel. It is often (but not always) in the form of a dot or a blade. To attain a proper sight picture and shoot with the greatest degree of accuracy, the shooter’s eye should be focused sharply upon the front sight while shooting, allowing both the rear sight and the target to blur somewhat.
Front Strap is the part of a revolver or pistol grip frame that faces forward and often joins with the trigger guard.
Full Metal Jacket or FMJ is a type of round in which in which the lead core bullet is encased in a harder metal jacket on the front and sides.
Furniture is slang for accessories added to the firearm.
GAP is in reference to Glock Auto Pistol, a type of ammunition.
Gas is the superheated air and other stuff produced by burning powder. Gas pressure is what sends the bullet downrange.
Gas Operated is a firearm that uses the energy from superheated gases to work the action.
Gauge is the bore size of a shotgun determined by the number of round lead balls of bore diameter that equals a pound. It is used like “Caliber” for the shotgun.
Ghost-Ring Sight is a type of aperture rear sight with a large opening and a thin rim that seems to fade out when the shooter looks through it. Sometimes installed on rifles and shotguns intended for home defense or police use.
Grains is the unit of weight measurement used for bullets and gunpowder. The more grains, the heavier the bullet. Powder is also measured by grains, but this is generally of interest only to re-loaders. There are 7000 grains to a pound.
Green Ammunition is ammunition that contains no lead in any component.
Grips are the handle used to hold a handgun. Often refers to the side-panels of the handle or the method by which the shooter holds the handgun.
Grip Panels are the interchangeable surfaces that are installed on the part of the gun that you hold. Users change grip panels to improve the look or feel of the firearm, or to personalize it so that the gun is more suited to a different hand size. Some grip panels are chosen for function, while others are chosen for looks. Common grip-panel materials are wood, plastic, and rubber.
Grip Safety is a passive, external safety typically located on the backstrap, which must be fully depressed to release the trigger. Most 1911-pattern pistols feature a grip safety.
Gripstraps are the exposed portion of a handgun’s frame, the front strap and backstrap, that provides the foundation for the handgun’s grip.
Grooves are the spiral cuts into the bore of a barrel that give the bullet its spin or rotation as it moves down the barrel. Technically is is the portion of the bore in a rifled barrel that has been machined away.
Group or Grouping are the gathering of holes in the target. The group size is measured by finding the bullet holes that are the furthest apart from each other and measuring from the center of one hole to the center of the other hole.The closer the holes, the better. Obviously the number of shots fired affect the group size. Typical numbers are three, five and ten. From a statistics viewpoint a three shot group is virtually meaningless as a measurement of firearm accuracy. Five shot groups are acceptable. Some advocate a seven shot group as a good tradeoff between economy and statistical relevance.
Gun is the common term for firearm.
Gunpowder is the chemical substances of various compositions, particle sizes, shapes and colors that, on ignition, serve as a propellant. Ignited smokeless powder emits minimal quantities of smoke from a gun’s muzzle; the older black-powder emits relatively large quantities of whitish smoke.
Hair Trigger is a trigger that breaks from an extremely light touch.
Half-Cock is the position of the hammer where the hammer is partially but not completely cocked. Many firearms, particularly older firearms, had a notch cut into the hammer allowing half-cock, as this position would neither allow the gun to fire nor permit the hammer-mounted firing pin to rest on a live percussion cap or cartridge. The purpose of the half-cock position has variously been used both for loading a firearm, and as a safety-mechanism.
Hammer is the part that rotates to provide the percussive impact on the primer. The firing pin may be struck by the hammer, or the firing pin may be a part of the hammer. Not all guns have hammers. Many guns are equipped with strikers: notably Glock pistols and the vast majority of bolt action rifles. Hammers may be exposed or shrouded, spurred or bobbed.
Hammer Bite is 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.
Hammer Spur is the thumb-piece on the top rear of the hammer that enables it to be manually drawn back to full cock.
Hammerless is a revolver or pistol design that actually have hammers but are fully encased inside the frames, hammer designs where the spurs have been removed for concealment, or striker-fired pistols that are truly hammerless.
Handgun is a synonym for pistol. designed to be fired while held in one or both hands, rather than while braced against the shoulder.
Handloads are cartridges assembled by an individual person from the individual components (primer, shell casing, gunpowder, and bullet) and are typically tailored specifically for their firearm.
Hardball is slang for a full metal jacket bullet with a round nose. The term is most commonly used in referring to .45 ACP caliber ammunition, but may be used for other calibers as well.
Heel (Of A Stock) is the top of the butt, when the gun is in position on the shoulder to be fired, is called the heel.
Heavy Trigger is a trigger that requires a lot of pressure to pull it past the break point. Rifles tend to have considerably lighter triggers than handguns, and even a heavy rifle trigger is often lighter than a light handgun trigger.
High-Capacity Magazine is an inexact, non-technical term indicating a magazine holding more rounds than might be considered “average.”
High Kneeling is a shooting position in which one or both knees are touching the ground, but the shooter is otherwise erect.
HMR is the acronym for Hornady Magnum Rimfire, a type of ammunition.
Hollow-Point Bullet is a bullet with a concavity in its nose to increase expansion on penetration of a solid target. some hollow-point’s are also designed to fragment as they expand. They are least likely to over-penetrate the target and harm an innocent bystander. Commonly used for self-defense.
Holster is a gun holder that may be strapped to a human body, or affixed to the inside of a pack or bag, or dropped into a pocket. A holster serves to protect the gun’s mechanisms and finish, to provide security by covering the trigger so it cannot be pulled inadvertently, and to present the grip of the gun at a constant angle for easy access. Some holsters also serve to obscure the outline of the gun so it may be more easily concealed. Typically made from leather or in plastic.
Hot Range is where a pistol can be carried loaded, also a range where the range master has given the order to commence fire.