A GLOSSARY OF FIREARMS TERMINOLOGY v1.6.1
Text Copyright 1997-1999 David S. Markowitz
Photography of the Colt SF-VI Copyright 1996 - '98 Josh Markowitz

I decided to write this glossary after being dissatisfied with the one on the NRA's web page. I wanted to come up with something much more extensive. I hope that I have succeeded in creating something more useful.  If you spot any errors, whether they are merely spelling goofs or technical mistakes, I would appreciate it if you would contact me at dsmjd@erols.com. (Positive feedback is also welcome, of course. <g>) Also, if you have any suggestions as to terms that I should include, but haven't, please pass them on to me.

Last updated 9/15/99.


Note: If a term appears in italics, that term also appears (or will be added) as an entry in this glossary.

ACP: (n.) "Automatic Colt Pistol." Proprietary term used by Colt to identify certain cartridges used in their semiautomatic pistols. E.g., .25 ACP, .32 ACP, .380 ACP, .45 ACP.

Airgun: (n.) A gun which shoots a projectile by using compressed air or CO2 as a propellant, instead of gunpowder.

Assault weapon: (n.) 1. A firearm capable of select-fire (q.v.) and firing an "intermediate cartridge", designed for military use. The first such assault weapons were used by the German Army in World War Two, and the name is a derivative of "Sturmgewehr," German for "assault rifle," a name created by Adolph Hitler. 2. A legal term as defined in the U.S. "Assault Weapons Ban," part of a bill enacted in 1994 which amended the Gun Control Act of 1968, 18 U.S.C. Section 922 et seq. For more details read my article "Understanding the Federal Assault weapons Ban".

Automatic: (adj.) 1. Used to describe a weapon which, using the energy produced from the firing of ammunition, will continue to load the chamber, work the gun's mechanism, and fire for as long as the trigger is pulled and ammunition remains in the magazine or feed belt. Also, "fully automatic." 2. Slang for semiautomatic.

Ballistics: (n.) The study of how projectiles fly. More specifically, external ballistics refers to how a projectile behaves after it leaves the barrel of a gun, while internal ballistics refers to the chemical and mechanical processes which occur with a gun after the trigger is pulled but before the projectile leaves the barrel. What happens when the bullet strikes a target is referred to as terminal ballistics.

Barrel: (n.) The tube on a gun which serves to guide the projectile during the initial portion of its journey to the target. A barrel may be smoothbored or rifled.

Bayonet: (n.) An edged weapon mounted on the muzzle end of a firearm as a backup weapon.  The first bayonets were essentially daggers which were stuck in the muzzle of a musket, so that it could be used as a pike in close combat.  This was superseded by the socket bayonet, which (naturally) features a socket that goes around the piece's barrel, so that the musket could be fired even while the bayonet was mounted.  Socket bayonets were used widely in the 18th and 19th centuries.  They have been replaced by knife bayonets, which are basically knives that can be mounted onto rifles or shotguns.  Bayonets have been made to fit muskets, rifles, shotguns, and even handguns.  Most bayonets are easily detached from the weapon, but some are semi-permanently mounted on the gun.  Examples of these include the Soviet SKS carbine and M1944 Omission-Nagant.

Bayonet lug: (n.) A fitting on a firearm to which a bayonet is attached.

Berdan primer: (n.) Invented by Colonel Hiram Berdan of the US Army in the 19th c., this is the most common type of centerfire primer manufactured outside the USA.

Birdshot: (n.) Small, round pellets loaded in a shotgun used for shooting at birds, small game, or clay targets. The large number of shot spread out when fired, making it easier to hit a small or moving target.

Bore: (n.) The inside of a barrel. May be smooth or rifled.

Boxer primer: (n.) Invented by the British Colonel Boxer in the 19th c., this is the most common type of centerfire primer used in the USA.

Black powder: (n.) The original formula for gunpowder. It is now called "black powder" to distinguish it from smokeless powder. It is a simple mechanical mixture consisting of 75% potassium nitrate (KNO3; AKA saltpeter), 15% sulfur (S), and 10% charcoal. It is much less powerful than smokeless powders, produces more fouling, and produces a large amount of smoke when ignited. It is considered obsolete for use in military firearms, but is still used widely in sporting guns and in blasting. It is designated as a Class A "low explosive." In contrast, smokeless powder is not an explosive, but a "flammable substance." Black powder can be ignited by a spark, static electricity, or concussion.

Brass: (n.) Term used to refer to metallic cartridge cases, taken from the material that they are most commonly made from. (Actually, cartridge bronze.)

Breech: (n.) The back-most end of the barrel. The opposite of muzzle.

Breechloader: (n.) A gun which loads through the breech end of the barrel. The advantages to being a breechloader include being able to load more quickly and with less effort, a greater rate of fire, and being able to easily load the gun from awkward positions, or while mounted. Until the invention of the metallic cartridge, most breechloaders were impractical. A major problem they had was severe gas leakage.

Buckshot: (n.) Small lead balls loaded in a shotgun, used for hunting game or for antipersonnel use. The smallest buckshot (number 4) is about .25 caliber; the largest (000) is about .36 caliber.

Bullet: (n.) The projectile fired from a rifle or handgun. The term does not encompass the entire round of ammunition. A bullet may be made of lead, lead alloyed with other metals (e.g., tin or antimony); a lead core surrounded by a jacket made of copper, cupro-nickel, gilding metal, brass or steel; or, infrequently, made of another metal, such as solid brass. Sometimes, lead bullets are surrounded by a paper patch.

Caliber: (n.) This is a term with several related meanings which can cause some confusion. 1. The internal diameter of a gun's barrel. This can be measured either in English units or in metric. The measurement can be taken in a rifled arm either land to land or groove to groove. E.g., in most .30-caliber rifles, the diameter of the bore land to land is .300 inches, while groove to groove it is .308 inches. 2. Sometimes, caliber is used as a synonym for cartridge. E.g., "This is a .30-30 caliber rifle." 3. When used in reference to artillery pieces, caliber is used to measure the length of the barrel. A 5 inch/50 caliber piece would have a barrel 50 times the bore diameter, or 250 inches long.

Cannon: (n.) See gun.

Carbine: (n.) 1. A short rifle, generally one with a barrel 22 inches in length or shorter.  2. Also used to refer specifically to the U.S. Carbine, Caliber .30 M1, which was adopted by the U.S. military in 1941, and which saw extensive use in World War 2, the Korean War, and Vietnam.  Note that the M1 Carbine is not a carbine version of the M1 Garand; they are entirely different designs using different ammunition.

Cartridge: (n.) One round of ammunition, consisting of the case, primer, powder charge, and projectile(s). There are several types: metallic, plastic, paper (which generally does not include a primer), rimfire, and center fire. (See this document for definitions of these other terms.)

Charger: (n.) See clip.

Choke: (n.) A slight constriction in the internal diameter of the bore near the muzzle end of the barrel. On shotguns, this is done to improve the pattern of the shot, to keep it from spreading out too quickly. Some rifled arms are also slightly choked as an aid to increased accuracy. This is especially true of precision airguns. The noted barrel maker Harry Pope made choked rifle barrels.

Clip: (n.)  A device used to rapidly load a magazine.  "Clip" is often used to refer to a magazine, but this is an improper use of the term.  There are two kinds of clips:  Stripper clips and en bloc clips:
 

Cock: (v.) To ready the mechanism of a gun for firing, e.g., as in "to cock the hammer."  (n.) Obsolete term for hammer.

Corto: (adj.) Italian for "short."  Seen as part of a cartridge designation.  E.g., 9mm Corto, which is the same as the .380 ACP.

Cupro-nickel: (n.) An silver-colored alloy of copper and nickel used to make bullet jackets. U.S. Ball, .30, M1906, and British .303 Small Arms Ammunition Ball MK. VII, for example, were made with cupro-nickel jackets.

Double action: (adj.) In reference to revolvers, "double action" means that it may be fired by either manually cocking the hammer, and then pulling the trigger, or by just pulling the trigger to cock the hammer and fire the piece. The Smith & Wesson Model 10 Military & Police and Ruger GP100 are double action revolvers.

"Double action" semiautos can be cocked for the first shot by pulling the trigger to cock the piece, then fire the gun. The SIG P228 and Walther P38 are double action semiautos.

Double action only: (adj.) DAO guns are those which are fired by using the trigger to first cock the hammer and then fire the piece for each shot. Between shots, the hammer rests forward, uncocked. Beretta makes a double action only version of their M92. Also, the Glock series of pistols are a species of DAO semiauto. The Smith & Wesson M640 is a DAO revolver.

Double-tap: (n.) A succession to two-shots fired rapidly from a semiautomatic pistol, rifle or shotgun, or a revolver. Also, as a verb, to describe the act of firing a double-tap.

Dram: (n.) Avoirdupois measure of weight equal to 27.34 grains. There are 16 drams per ounce; 256 drams per pound.

Dram-equivalent: (adj.) Used in connection with shotgun shells to describe how powerful they are, by equating their power with an equivalently powerful black powder load. The higher the number, the more powerful the shell is. When shotgun shells were loaded with black powder, the powder charge was measured in drams. Around the turn of the century, ammunition makers were transitioning to loading with smokeless powder, and created the term "dram-equivalent" so that shooters would know how powerful their shells were, relative to the old black powder loads. The term has stuck around since then.

Firing pin: (n.) Part of a gun which strikes the primer, firing the gun. Motion may be imparted to the firing pin by striking it with a hammer, or it may itself be spring-loaded and released.

Foot-pound: (n.) A unit used to measure the kinetic energy possessed by a bullet. One foot-pound is enough energy to raise an object with a mass of one pound one foot off the ground. See also, joule.

Flash hole: (n.) 1. The hole running through the wall of the barrel on a flintlock arm, providing a conduit from the pan to the main charge. Fire passes through the flash hole from the pan to the main charge, firing the gun. 2. The hole between the primer pocket in a metallic cartridge and the portion of the cartridge holding the powder charge.

Flintlock: (n.) A firing mechanism used primarily on muzzleloaders, using the shower of sparks created when a piece of flint strikes a steel frizzen to ignite a priming charge, which in turn ignites the main powder charge.

Frizzen: (n.) The part of a flintlock which is struck by a piece of flint, producing a shower of sparks. At one time it was called a hammer.

Garand: (n.)  Common name given to the U.S. Rifle, Caliber .30, M1.  Invented by John C. Garand, a civilian employee of the U.S. Army's Springfield Armory.  Adopted in 1936, it became the first semiautomatic rifle adopted as the general issue weapon for any military force.  It was the main U.S. military rifle during World War Two, and remained so until the early 1960s (although it was officially superseded in 1957 by a derivative, the M14).  The Garand is gas-operated, feeds from an 8 shot magazine, and is loaded with an en bloc clip.  During WW2, General George S. Patton referred to the M1 in a letter to Springfield Armory as "the greatest implement of battle ever devised."  Note that the M1 Carbine is a completely different design and fires a different cartridge.

Gauge: (adj.) A way to describe the size of a gun's bore, used mostly for shotguns.  For example, a 12 gauge shotgun has a bore equal in diameter to a pure lead ball weighing 1/12th of a pound.  A 20 gauge shotgun has a bore equal in diameter to a lead ball weighing 1/20th of a pound.  So, using this system, as the gauge goes up, the bore diameter goes down.  This is the opposite of caliber.

Grain: (n.) Avoirdupois unit of measure equal to 1/7000th of one pound. In the U.S., grains are used to measure the weight of bullets and powder charges.  Note that a grain is not the same a granule of powder.

Groove: (n.) The recessed portion of rifling.

Gun: (n.) 1. A weapon which propels a projectile out through a tube, known as the barrel. by means of the expansion of gas created by the combustion of a propellant, or through compressed air or carbon dioxide. 2. In military usage, an artillery piece which can fire shells over long distances with flat trajectories, i.e., a cannon. C.f., mortar, howitzer.

Hammer: (n.) The part of a gun's mechanism which, after being cocked, flies (usually) forward to strike the firing pin or primer, thus firing the gun.

Hand: (n.) The part of a revolver which turns the cylinder as the gun is cocked.

Handgun: (n.) A gun designed so that it may be held and fired in one hand. See pistol, revolver.

Hollowpoint: (n.) A type of bullet with a hollow cavity formed into its nose, designed to expand when it hits a target. The use of hollowpoints is banned in international warfare by the Hague Convention of 1899 (NOT the Geneva Convention, which covers the use of poison gases and treatment of POWs.) Abbreviated as "HP."

Howitzer: (n.) An artillery piece which is used to fire projectiles over medium ranges on high trajectories. C.f., gun, mortar.

Intermediate cartridge: (n.) A cartridge designed to allow controllable automatic fire from a rifle, yet more power than a submachinegun. The first such intermediate round was the 7.92x33mm developed by the Germans during World War II. It was primarily used in the MP-43/MP-44/Stg.-44. It is referred to as "intermediate" in that it is more powerful than a pistol round, e.g., 9mm Parabellum, but less powerful than a full-power rifle cartridge, e.g., the 7.92x57mm.

Iron Sights: (n.)  Metallic sights on a gun.  The term is used to differentiate them from optical sights (scopes).

Jacket: (n.) With the advent of smokeless powders, bullets could be propelled at much greater speeds than with black powder. This necessitated sheathing the lead core of the bullet in a harder metal, the jacket. This may be made of copper, cupro-nickel, gilding metal, or steel. The jacket prevents the lead core from melting and leaving large deposits of lead fouling in the bore.

Keith-style bullet: (n.) See semiwadcutter.

Kurz: (adj.) German word meaning "short."  Used in cartridge designations, such as 9mm Kurz, which in the USA is known as the .380 ACP.

Land: (n.) The raised portion of rifling.

Lock: (n.) The firing mechanism of a gun, usually a muzzleloader, but also some 19th Century breechloading rifles, e.g., the Sharps.

Lock time: (n.) The amount of time between when the trigger is pulled and the gun goes off. Generally, the faster the lock time the better, because this makes it easier to shoot accurately. In order to obtain the fastest lock time, some guns have been built which set off the primer via an electric impulse, rather than through mechanical means.

Luger: (n.) American name for the German "Parabellum" semiautomatic pistol introduced in 1900.  The Parabellum was designed by Georg Luger, and based on the earlier Borchardt pistol.   The official German military nomenclature was "Pistole '08" or "Po8."  At first, it was chambered for the 7.65mm Parabellum round.   Soon, it was modified to use the 9mm Parabellum cartridge, which is what most people refer to today when talking about a "9mm."  "Luger" is now a trademark owned by the Stoeger Arms Co.

M1911: (n.) The official US military designation for the Colt .45 semiautomatic pistol adopted by the US in 1911.   The gun was designed by John Moses Browning, and produced by Colt.  During trials, the Browning-Colt design beat out several competing designs, including one from Savage and a .45 caliber version of the German Parabellum ("Luger").   The M1911 saw its first combat in the Philippines and then in World War I.   Early use showed that it could be improved and in 1921 the M1911A1 was introduced, which featured a few changes like a reocontoured frame, shorter trigger, and a rounded backstrap.  The M1911A1 remained the standard US military handgun until it was replaced in the 1980s by the Beretta M9.  However, it remains very popular with civilian shooters in the US, and has been modified extensively to update it to conform to more modern theories of handgun usage.

Magazine: (n.) A device for holding cartridges to be loaded into a repeating gun's chamber.  A magazine can be a fixed, non-removable part of a gun, or it can be a detachable box.  Sometimes improperly referred to as a clip.

Magnum: (adj.) From the Latin for "more."  It's a term applied to certain cartridges which generate higher velocity and energy when compared to other rounds firing bullets of the same diameter.  E.g., the .357 Magnum shoots bullets at much higher velocities than the .38 Special (which actually shoots .357" bullets).  Basically, it's a marketing term.

Makarov: (n.) The standard Soviet, and now Russian military sidearm since the 1950s.  Official designation is "PM" for "Pistolet Makarova."  It was designed by Mr. Makarov, is a blowback operated semiautomatic pistol, which fires the 9x18mm Makarov cartridge, and holds 8 rounds in the magazine.  It has also been made in the Peoples Republic of China, East Germany, and Bulgaria. 

Mississippi Rifle: (n.) Slang term for the U.S. Rifle M1841, a .54 caliber muzzleloading rifle. The name comes from their use by a group of U.S. Volunteers from Mississippi who were commanded by Jefferson Davis in the Mexican War. Some were later rebored to .58 caliber.

Mortar: (n.) An artillery piece used to fire shells over short ranges at very high trajectories. C.f., gun, howitzer.

Musket: (n.) A smoothbore military muzzleloading shoulder arm. Muskets were the worldwide standard in military infantry weapons before the adoption of the rifle as standard. The advantage muskets possess over rifles is that being smoothbores and using undersize bullets, they could be loaded much more quickly than a muzzleloading rifle. The downside to this is that muskets were very inaccurate compared to rifles. Shooting at an individual target, they possess an effective range of about 50 yards. For this reason, massed volley fire was used, with the idea that if you throw enough lead at the enemy some of the bullets will strike home.

Muzzle: (n.) The end of the barrel which the fired projectile comes out. The opposite of breech.

Muzzleloader: (n.) A gun which loads through the muzzle. Before the invention of the metallic cartridge, most firearms were muzzleloaders.

Pan: (n.) The part of a flintlock which holds the priming charge of black powder.

Parabellum: (n.) Latin word meaning "for war."  It is actually the proper name of the semiautomatic pistol commonly known in the USA as the "Luger."

Patch: (n.) 1. A piece of greased cloth used to wrap a round ball used as the bullet in a muzzleloading rifle. 2. A piece of lubricated paper wrapped around the bullet in cartridges used in some black powder cartridge rifles.  In either case, the patch fills in space between the bullet and the bore, serves as a gas seal, prevents leading, and engages the rifling.

Pellet: (n.) 1. A single piece of birdshot or buckshot. 2. The bullet fired from an airgun.

Pistol: (n.) Traditionally, a handgun not a revolver, e.g., a single-shot, multi-barrel, or semiautomatic. In current use the term includes revolvers.

Primer: (n.) That part of a cartridge which is struck by the gun's firing pin, detonates, and thus ignites the powder charge. There are two main types of priming systems currently in use -- rimfire and centerfire. In a rimfire cartridge, e.g. .22s, the priming compound is contained in the hollow rim. In a centerfire primer, the compound is in a small metal cup inserted into the base of the cartridge case. There are two types of centerfire primers. The first, or Boxer primer, is made up of the cup and the anvil, and the priming compound sandwiched between the two. The other, or Berdan, omits the anvil from the primer, instead, it is integral with the cartridge case.

Quaker Gun: (n.)  Not really a gun at all.  During the War of Northern Aggression (known in some parts as the Civil War), both sides would take tree trunks, paint them black, and position them so that they appeared to be artillery pieces.  By doing so, they could fool the other side into believing that they had more artillery than they really did.

Revolver: (n.) A repeating firearm in which the ammunition is held in a multi-chambered cylinder, which is rotated to bring each chamber in line with the barrel. Most revolvers are handguns, although shoulder-fired arms have been made using this sort of mechanism. See a picture of a Colt SF-VI revolver.

Rifle: 1. (n.) A shoulder-fired long gun which has a rifled (See Rifling.) barrel. C.f., shotgun or musket. 2. (v.) To form the rifling in a gun barrel.

Rifling: 1. (n.) Spiral grooves formed into the bore of a gun barrel, which cause the bullet to spin upon firing, thus stabilizing it much like a thrown football. Rifling may be cut, swaged, or forged into the barrel. 2. (v.) The process of forming the rifling in the bore.

S&W: (n.)  Abbreviation for Smith & Wesson, prominent American maker of revolvers and firearms since the 1850s.   S&W's introduced the first commercially-produced breechloading revolver.

Scout rifle: (n.) A concept created by eminent gun writer Col. Jeff Cooper. A scout rifle, generally, is a bolt action carbine firing a medium power round suitable for taking large game (e.g., .308), fitted with a long eye-relief telescopic sight mounted on the barrel, and a back up set of iron sights.

Semiautomatic: (adj.) Term used to describe firearms which use part of the energy produced when the gun is fired to work the mechanism and ready the gun for the next shot, so long as ammunition remains in the gun. A semiautomatic weapon will fire only one shot each time the trigger is pulled; the trigger must be released between each shot. C.f., "automatic."

Semiwadcutter: (n.) A type of bullet shaped like a cylinder with a truncated cone on one end.  The base of the cone is slightly smaller in diameter than the diameter of the bullet, so a shoulder is formed where they join.  Semiwadcutters are used in target shooting, hunting, and defensive applications, especially in jurisdictions where hollowpoints are prohibited by law.  Also known as a "Keith-style" bullet, after gun writer Elmer Keith, who espoused their use for hunting.

Shotgun: (n.) A shoulder arm designed primarily for shooting a large number of small projectiles at once. The shot spread out, making it easier to hit a moving target. Shotguns are used with birdshot to hunt birds (obviously) and small game. They can also be loaded with buckshot for hunting larger game (up to deer-sized) or anti-personnel use, or slugs, a single projectile loading used for hunting big game. Note that while a shotgun can fire more than one projectile per cartridge, this is different than an automatic weapon, which although it shoots more than one projectile per pull of the trigger, does so in succession.

Single action: (adj.) When applied to revolvers, a gun which must be manually cocked before firing each shot. Examples of single action revolvers include the Colt "Peacemaker," and the Ruger Blackhawk.

In reference to semiautomatic pistols, "single action" means that the gun must be cocked before firing the first shot. The gun is then cocks itself for each subsequent shot. The Colt M1911A1 and Browning Hi Power are single action pistols.

Sling: (n.) A fabric or leather strap used for carrying a gun. A sling may also be used as a shooting aide, when wrapped around the arms properly.

Smokeless powder: (n.) Modern gunpowder, invented during the 1880s by the Frenchman M. Vielle. Smokeless powder has either a nitrocellulose or nitroglycerin base, or both (in which case it is referred to as "double based"). Like black powder, it is black in color, but this is generally due to a graphite coating which improves metering. Smokeless powder is a flammable substance, rather than a low explosive, like black powder, and is progressive burning. Its burning rate can be controlled by the shape and size of the granules. Faster burning powders (e.g., Bullseye™) are generally used in pistols, while slower powders (IMR 4064™) are used in rifles.

Smoothbore: (n.) A gun barrel which is not rifled. Shotguns are smoothbored. So is the 120mm cannon on the M1A1 Abrams tank.

Softpoint: (n.) A type of jacketed bullet in which the soft lead core is exposed at the tip, so that upon impact with the target the bullet deforms to cause more damage. Most bullets designed for hunting are softpoints.

Sturmgewehr: (n.)  German for assault rifle.  See assault weapon.

Submachinegun: (n.) A shoulder arm firing a pistol cartridge and capable of automatic fire. The first such weapon was the Italian Villar-Perosa, introduced during World War I. This weapon was not a great success, but the German Bergmann MP-18, which appeared on the scene shortly thereafter, was.  Submachineguns in common use today include the Uzi, produced by Israel Military Industries, and the MP-5, made by Heckler & Koch.

Stock: (n.) Basically, the handle by which one holds a gun. The action, or mechanism of a gun will be mounted in or attached to the stock, which is usually made of wood, but may be plastic, a composite, or even metal.

Timing: (n.) The alignment of the chambers in a revolver with the bore. In a revolver which has seen a lot of use, the timing can be "off," so that the chambers do not perfectly align with the bore, causing the gun to spit lead from the barrel-cylinder gap.

Trajectory: (n.) The vertically curved path taken by a bullet after it leaves the barrel of a gun. If you draw an imaginary straight line exactly parallel to the center of the bore, the bullet will fall away from that line.

Underhammer: (n.) A type of lock in which the hammer pivots in a vertical arc, striking the nipple on the underside of the barrel. Since the nipple's flash channel goes straight into the powder at the breech end of the barrel, ignition time is very fast. For this reason, and because it gets the hammer out of the way, underhammer locks are commonly used on muzzleloading benchrest rifles which are used for target shooting, and where accuracy is the goal.

Wadcutter: (n.) A type of bullet shaped like a cylinder with flat ends.  It is primarily designed for target shooting with pistols.  The flat end enables it to punch a clean hole in the paper target and make scoring easier.  Wadcutters may be hollow-based, double-ended, or bevel-based.   They are typically cast or swaged out of a lead alloy and usually don't have a jacket.


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