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Glossary of Firearms Terms


Action:† The mechanism of a firearm directly behind the barrel, by which a gun is loaded, locked, fired, unlocked, extracted and ejected.

Anvil:† That part of the cartridge primer which is a solid surface, against which the firing pin strikes to set off the priming powder.

Autoloading:† See Semi-AutoMatic

Ball:† The round lead missile fired by smoothbore firearms. (The term is used today when referring to some types of bullets fired from rifled barrels).

Ballistic Coefficient:† A number which indicates how a bullet's shape, length, weight, diameter and nose design affect its stability, velocity and range against air resistance.

Ballistics:† The study of what happens to moving† projectiles in the barrel and in† flight - their trajectory, force, impact and penetration. “Internal ballistics” refers to what happens inside the barrel before the bullet or shot leaves the muzzle; “external ballistics” is what happens after the bullet or shot leaves the barrel and travels to its final point of impact and “terminal ballistics” is what happens to the bullet at the final point of impact.

Barrel:† The metal tube of a firearm made from iron or steel, through which the bullet or shot charge passes when the firearm is fired.

Base Wad:† The paper filler at the rear of the powder charge of the shotgun shell.

Battery:† The metal arm of a flintlock mechanism, against which flint strikes to create sparks in the flashpan (also called the “frizzen”).

Beavertail:† A wide, flat fore-end of a rifle or shotgun.

Bedding:† That part of the stock into which the barrel fits.

Belt:† The narrow band around the rear section of a cartridge case just forward of the extractor groove. (The belt arrests the progress of the case into the chamber and controls headspace.)

Berdan Primer:† See Primer

Black Powder:† A finely ground mixture of three basic ingredients - saltpetre (potassium nitrate), charcoal (carbon) and sulphur.

Blown Pattern:† A shotgun pattern with erratic shot distribution, generally caused by gas escaping past the wads and getting into the shot.

Bluing:† A process of treating metal gun parts in a bath of metallic salts and water, which colors them blue to prevent rust.

Boattail:† The tapered rear end of a bullet. (Also called “taper heel", this design is used to increase ballistic efficiency at long range.)

Bolt:† A steel rod-like assembly which moves back and forth in a bolt action, sealing the cartridge in the chamber during firing.

Bolt Face:† The forward end of the bolt which supports the base of the cartridge and contains the firing pin.

Bore:† The tunnel down the barrel of a firearm through which the projectiles travel.

Bore Diameter:† The measurement from one side of the bore to the other. In a rifled barrel this means measurement of the bore before the rifling grooves are cut.

Breech:† The rear end of the barrel (in modern arms, the portion of the barrel into which the cartridge is inserted. See Chamber.

Breechblock: The part in the breech mechanism that locks the action against the firing of the cartridge.

Breechloader:† A firearm loaded through the breech.

Buckshot: Large lead pellets used in shotshells.

Bullet: A single projectile fired from a firearm.

Butt: The rear end of a rifle or shotgun. (The portion that rests against the shoulder.)

Buttplate: A plate which covers the butt. (Some steel buttplates have trap doors covering a recess for storage of cleaning equipment.)

Calibre: The diameter of the bore of a rifle before the rifling grooves are cut.

Cannelure: A groove around the circumference of a bullet or case. (For example, the lubrication grooves of lead bullets, or the grooves into which the mouth of the cartridge case is crimped, or the extractor grooves of the† rimless† or belted case.)

Cant: To tilt or lean a gun to the side when aiming.

Cap: See Percussion Cap.

Carbine: A light short-barreled riffle.

Cartridge: A case, usually made of brass or copper, containing the powder charge, the primer and the bullet. (Before development of the metallic cartridge, the term was used to mean a roll or case of paper containing powder and shot. Modern cartridges are generally classified in three categories — “centrefire metallics”, rimfires” and “shotshells”. Centrefire metallics† include all metal cartridges that have primers in the center of the base. Rimfires include all cartridges in which the priming powder is sealed in the soft rim around the base. Shotshells include all cartridges that contain shot, or small pellets, instead of a single bullet.)

Centre-Fire: See Cartridge.

Chamber: The enlarged portion of the barrel at the breech in which the cartridge is placed ready for firing.

Checkering: A diamond-like patter on fore-ends and grips of firearms. (The diamonds are made by cutting crossing lines into the material with special tools.)

Choke: The constriction at the muzzle of a shotgun barrel by which the spread of the shot pattern is controlled.

Cup: A detachable metal case designed to hold a number of cartridges for loading into the firearm.

Cock: To set the action into position for firing. (On some firearms the action has an intermediate position called half cock. On early weapons such as the flintlock and percussion cap, the hammer was called a cock.)

Comb: The upper edge of a rifle or shotgun stock where the cheek rests.

Cone: The sloping portion at the front end of a shotgun chamber in which the chamber diameter is decreased to the diameter of the muzzle. Also, the rear portion of the choke at the muzzle of a shotgun.

Conical Bullet A cone-shaped bullet.

Cordite: A double-base smokeless powder made of nitroglycerine and guncotton which is used in the form of long, stringy cords.

Core: The part of† a bullet that is covered by a jacket.

Corrosion: The gradual eating away of the metal parts of a firearm caused by rust.

Creep: The movement of the trigger before it releases. (Also called drag or crawl.)

Crimp: The portion of a cartridge case that is bent inward to hold the bullet in place, or in the case of shotshell, to hold the shot charge in place.

Cross Hairs: The sighting lines† in† a telescopic sight.

Damascus Barrels:† Barrels made of strips of iron and steel welded together in a spiral fashion. (Modern ammunition should not be used in such firearms.)

Deterrent: A material added to an explosive to slow its burning rate.

Double-Base Powder: A rapidly burning powder made by absorbing nitroglycerine into† nitrocellulose (guncotton). (Cordite is a double-base powder.)

Doughnut Pattern: A shotgun pattern with a hole in the middle generally caused by the interference of the top wad.

Down Range: The direction from the shooting position to the target on a range. See Range.

Drift: The departure of a bullet or shot charge from the normal line of flight. (This can be caused by wind or the unbalanced spinning of the bullet.)

Drilling: A three-barrel gun with a rifle barrel beneath two shotgun barrels. (Generally of German manufacture.)

Ejector: The mechanism which throws the cartridge case free from the gun.

Elevation: The degree of adjustment of a rear sight or scope reticule necessary to cause the bullet to strike higher on the target.

Energy: The amount of work done by a bullet, expressed in foot pounds.

Erosion: The wearing away of a barrel’s metal surface by a bullet or shot charge or by the heat of powder gases.

Extractor: A hook device which pulls the case out of a chamber as the breech mechanism is opened. (The extractor generally brings the case within reach of the ejector, which then flips it out of the gun.)

Feed: The action of moving live cartridges from the magazine of a firearm into the chamber.

Firing Pin: The part of the breech mechanism which strikes the primer of the cartridge. (In most firearms, the firing pin is part of the bolt assembly.)

Flinch: To move or jerk a firearm involuntarily while shooting.

Flint: A piece of stone held in the cock of a firearm. (When it strikes the steel battery, or “frizzen”, this causes a shower of sparks to fall into the flashpan and ignite the powder.)

Flintlock: The gunlock of early firearms in which flint is thrown against steel, causing sparks to ignite the powder charge.

Floor Plate: The detachable metal plat at the bottom of the cartridge magazine of a bolt action rifle. (The floor plate is usually hinged at the front and held by a release spring located just ahead of the trigger guard.)

Fore-End: The forward portion of a shoulder-arm stock. (Located under the barrel, the fore-end serves as a hand-hold.)

f.p.s.: Abbreviation for feet per second. A term used in expressing the velocity of a bullet.

Frizzen: See Battery.

Fulminate Of Mercury: A highly sensitive explosive used as a primer compound.

Gain Twist: Barrel rifling which increases in pitch from the breech to the muzzle to accelerate the spin of a bullet.

Gas Check: A metal cup placed on the end of a lead bullet to protect the lead against the hot gases of the burning powder charge.

Gas Port: A small hole in the barrel of a gas-operated firearm through which expanding gases escape to power the autoloading system.

Gauge: Measurement of shotgun bores derived from the number of bore-sized balls of lead to the pound. For example, 12 balls which fit the bore of a 12-gauge shotgun weigh one pound.

Grip: The small portion of the stock gripped by the trigger hand.

Grip Cap: A cap fastened over the end of a pistol grip on a rifle or shotgun stock.

Grooves: See Rifling.

Group: A series of shots fired with the same sight setting and the same aim.

Half Cock: See Cock.

Hammer: The part of the action that drives the firing pin forward.

Hammerless: Refers to a firearm whose hammer and striker are concealed within the metal frame.

Hand Cannon: On a variety of small, crude cannons used in the early 15th century.

Hangfire: Delay in firing a cartridge after the firing pin has struck the primer.

Headspace: The distance between the base of the cartridge and the face of the bolt or breechlock. (This is determined by the rim of rimmed cartridges, the belt of belted cartridges and the shoulder or rimless cartridges).

Heel:† The rear end of the upper edge of a gunstock. Also the base of a bullet.

High Intensity:† Refers to cartridges having velocities of 2,700 per second (822.96 metres per second) or more.

High Power:† A term applied to the first smokeless powder cartridges with velocities of approximately 2,000 feet per second (609.6 metres per second).

Holding:† The action of keeping the sights on the target while applying pressure to the trigger.

Hollow Point:† A bullet with a nose cavity designed to increase its expansion on impact.

Igniting Charge:† The charge used to ignite the propelling charge. (See Primer).

Inertia Firing Pin: A firing pin which moves† freely forward and backward in the breechblock. (The striker impels it forward while the explosion of the primer impels it backward).

International Ballistics: See Ballistics.

Iron Pyrites: See Pyrites, Flint.

Jacket: The outer covering over the inner metal core of a bullet.

Jaws: The vise-like device on a flintlock hammer used to hold the flint.

Jump: The amount of change in the bore axis, measured both vertically and horizontally, while the projectile moves from the chamber to the muzzle when it is fired.

Kentucky Rifle: A flintlock rifle with a long barrel and short, crooked stock.

Keyholing: The failure of a bullet to remain balanced in flight so that it enters the target sideways, leaving an elongated opening.

Kick: The backward movement of a firearm generated by the discharge of the projectile. See Recoil.

Knurled Surface: A metal surface which contains a pattern of ridges or beads. (This rough surface aids grasping a metal part to move it.)

Lands: In the rifling of a bore, the uncut portions of the barrel’s inner surface left after the rifling grooves have been cut into the metal. See Rifling.

Leading: Fouling of a firearm bore by metal particles from bullets adhering to the metal surface caused by heat or friction.

Lede: The bevelled portion of the rifling at the rear end of the barrel (and the forward portion of the chamber) where the bullet first engages the lands.

Length Of Pull: The distance from the front trigger of a shotgun to the centre of the butt.

Lever Action: An action operated by a lever located underneath it. (A secondary purpose of the lever is to serve as a trigger guard.)

Line Of Bore: An imaginary straight line through the centre of the bore of a firearm extending to infinity.

Line Of Sight: An imaginary straight line from the eye through the sights of a firearm to the target.

Load: A charge of powder, a projectile or a cartridge. Also, to prepare a gun for firing by inserting ammunition into it.

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

Lock: The firing mechanism of a a muzzle-loading weapon. In breech-loading firearms, the lock is the firing mechanism and breech-sealing assembly.

Locking Lugs: A series of projections on the bolt of a firearm designed to fit into corresponding slots in the receiver to lock the action in closed position for firing.

Lockplate: A metal plate on which the firing mechanism is mounted on percussion and earlier firearms.

Lock Time: The interval of time between trigger release and the detonation of the primer. (Also called lock speed.)

L.R.: Abbreviation for long rifle.

Machine Gun: A firearm which continuously fires ammunition at a high rate of fire when the trigger is pulled only once. See Automatic.

Magazine: The part of a repeating firearm which holds the cartridges or shells in position ready to be loaded one at a time into the chamber. (The magazine may be an integral part of a firearm or a separate device attached to the action.)

Magnum: A cartridge or shell with greater power than normal (i.e. .300 magnum rifle, 3 inch magnum shotshell).

Mainspring: A strong spring which activates the striker or hammer of a firearm.

Match: A long cord of hemp, flax or cotton, saturated in saltpetre, which burs slowly without a flame. (It was used to ignite powder in early firearms.)

Matchlock: A firearm action which relies upon a serpentine or S-shaped piece of metal to hold a smoldering match. By pressing the lower end of the serpentine, the upper end holding the burning match contacts the priming powder in the pan.

Metal Cased: A bullet with a lead core and a solid metal jacket.

Metallic Cartridge: A cartridge with a metallic case. (Early cartridge cases were made of linen, paper, etc.)

Metallic Sight: A non-telescopic firearm sight.

Mid-Range: The point in the trajectory halfway between the muzzle and the target.

Millimetre: A metric measurement equalling .03907 inches. (Its abbreviation is mm.)

Misfire: Failure of a cartridge to discharge after the firearm’s firing pin has struck the primer. See Hangfire.

Mouth: The open end of a cartridge case into which the bullet is inserted.

Mushroom: The shape many bullets assume when the tip expands upon striking. (Sometimes called mushroom bullets.)

Musket: A smoothbore shoulder gun (commonly used by military in the 17th, 18th and 19th centuries.)

Musketoon: A musket shortened for cavalry use.

Muzzle: The forward end of a barrel.

Muzzle Blast: The violent disturbance in the atmosphere after discharge of a firearm, caused by release of powder gases into the air.

Muzzle Brake: A slotted device attached to the muzzle which softens the kick of the firearm.

Muzzle Energy: The energy of a bullet as it emerges from the muzzle. (Usually expressed in foot pounds.)

Muzzle Flash: The bright flash at the muzzle of a firearm resulting from burning of gases.

Muzzeloader: A firearm that is loaded through the muzzle.

Muzzle Velocity: See Velocity.

Naked Bullet: A bullet not covered by a metal jacket or patch.

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.

Needle Gun: The first rifle known to use a bolt action.

Nipple: A small metal tube extending through the breech of a percussion firearm through which the flame passes from the percussion cap to fire the powder charge.

Nose: The point of a projectile.

Obturation: The expansion of the cartridge case which seals the chamber preventing gases from escaping.

Open Sight: A non-telescopic firearm sight. See Sight.

Optical Sight: Usually a telescopic firearm sight. See Sight.

Over-And-Under Gun: A firearm with two or more barrels placed one over the other.

Pan: The small dished container located on the side or top of a matchlock, wheel-lock or flintlock forearm used to hold the priming powder charge.

Parallax: The displacement of an object viewed from two different position. (For example, when using a telescopic sight, the apparent movement of the reticule in relation to the target when the eye is shifted to a different position.)

Parkerizing: A non-reflecting, rust-preventive finish used on the metal of firearms.

Patch: A piece of leather or cloth. The patch is greased and placed around a bullet before ramming it down the barrel of a muzzleloader.

Patch Box: Covered compartment in the buttstock of a muzzle-loading rifle used to carry patches or other small items.

Pattern: Distribution of shotgun pellets. This is measured at a standard distance of 40 yards (37 m) using a 30 inch circle (762 mm). (A full choke charge should throw a patter of at least 70 percent of the shot into the 30 inch circle at a distance of 40 yards.)

Penetration: The distance travelled by a projectile from the point where it strikes the target to the point where it stops.

Pennsylvania Rifle: See Kentucky Rifle.

Percussion Cap: A small metal explosive-filled cup which is placed over the nipple of a percussion firearm. (As the cap is struck by the hammer, it explodes and sends a flame through the flashhole in the nipple to the main powder charge.)

Pistol Grip: See Grip.

Pitch: The angle of the barrel of a rifle or shotgun away from the angle of the stock. (It is measured by placing the butt of the stock on the floor and measuring the angle of the muzzle away from a line perpendicular to the floor.)

Powder: The general term for any propellant used in firearms which burns upon ignition. (The two major types are black powder, which is a physical mixture of charcoal, sulphur and saltpetre, and smokeless powder, base of the bullet, chamber and bolt face of the rifle.)

Prime: To prepare or charge a muzzle loader for firing.

Primer: The collective term for the chemical primer compound, cup and anvil which, when struck, ignites the powder charge.

Primer Cup: The housing in a shotgun cartridge base which holds a primer.

Primer Pocket: The depression in the base of a centrefire cartridge which contains the primer.

Priming Pan: See Pan.

Projectile: A bullet or shot in flight after discharge from a firearm.

Propellant: The chemical substance which imparts movement to the projectile in a firearm.

Pumpkin Ball: A large round ball of lead used in shotguns. (These projectiles are the same size as the shotgun bore.)

Pyrites: A mineral used to produce sparks in primitive firearms. (It was replaced by flint.)

Ramrod: A wood or metal rod used to force the wad and bullet down the barrel of a muzzle-loading firearm.

Range: The distance travelled by a projectile from the firearm to the target. “Pointblank range” is the distance a projectile will travel before it drops the extent that sight adjustment is required. “Effective range” is the greatest distance a projectile will travel with accuracy. “Extreme range” is the maximum distance a projectile will travel. Also, a facility designed for the safe shooting of firearms.

Receiver: The metal frame of a rifle or shotgun which contains the breech, locking mechanism and reloading mechanism.

Receiver Ring: The portion of the receiver which is threaded so the barrel can be attached to it.

Receiver Sight: A sight attached to the receiver.

Recoil: The backward force of a firearm caused by expansion of powder gases which also impels the bullet out of the barrel. Recoil is measured in foot pounds. See Kick.

R.F.: Abbreviation for Rimfire.

Rifle: A shoulder firearm with a rifled barrel designed to fire one projectile at a time. See Rifling.

Rifled Slug: A large, single projectile used in shotguns.

Rifling: Spiral grooves cut into the inside barrel surface to cause a bullet to spin, thereby stabilizing it. The cut-away portions of the rifling are called Grooves and the uncut portions are called Lands. See Lands and Grooves.

Rim: The edge on the base of a cartridge case which stops the progress of the case into the chamber. (It’s also the part of the case the extractor grips to remove it from the chamber.)

Rimfire: A cartridge in which the priming compound is contained in the rim at the base of the cartridge. (See also Cartridge.)

Safety: A device that blocks the firing mechanism of a firearm.

Sear: The part of a firearm which links the trigger and the firing pin and releases it when the trigger is pulled.

Sectional Density: The relationship between the weight of the bullet and the cross-sectional area.

Semi-Automatic: An action which fires, extracts, ejects, reloads and cocks with each separate pull of the trigger and is powered by the propellant gases. (Also called autoloading.)

Serpentine: See Matchlock.

Setscrew: A screw that regulates the amount of pressure needed to release the sear.

Shotgun: A firearm with a smooth bore designed to fire small pellets called shot or rifled slugs.

Shotshell: See Cartridge.

Shoulder: The sharply sloping portion of the cartridge case joining the body and neck. (Found only on bottleneck shaped cartridge cases.)

Sight: The device on a firearm designed to help the shooter aim accurately.

Slack: The amount of movement in a trigger mechanism before it engages the sear.

Sling: A strap used to carry and aid in shooting a rifle.

Sling Swivel: A metal loop, sometimes detachable, by which the sling is attached to the firearm.

Small Bore: Generally refers to a .22 calibre firearm.

Small-Of-The-Stock: The narrow portion of the stock between the comb and the receiver of a shoulder firearm.

Smokeless Powder: See Powder.

Smooth Bore: A firearm with a bore that is not rifled.

Snap Shot: A quick shot taken without deliberate aim.

Spanner: A small metal wrench used to wind the mechanism of a wheel-lock.

Spent Bullet: A projectile which has lost nearly all its energy and lacks the force needed to penetrate the target.

Spitzer: A bullet with a sharp point for better stability during flight.

Stock: The part of a shoulder firearm by which it is held for firing and into which the metal parts are fitted.

Straight-Pull Action: A bolt action in which the bolt is pulled and pushed straight backward and forward.

Striker: The front part of a firing pin which strikes the cartridge.

Swivel: See Sling Swivel.

Tang: A metal strip extending rearward from a rifle or shotgun receiver to attach the action to the stock.

Throat: The forward portion of the chamber where it is tapered to meet the bore.

Toe: The bottom part of the butt of a rifle or shotgun.

Trajectory: The path a bullet travels from muzzle to impact.

Trigger: The part of a firearm mechanism which releases the firing pin.

Trigger Guard: A metal loop around the trigger designed to protect it.

Trigger Plate: The metal part under the receiver of a rifle or shotgun through which the trigger projects.

Trombone Action: A pump or slide action.

Turn-Bolt Action: A bolt action which is locked by pressing the bolt handle in and down, thereby turning its locking lugs into the receiver.

Twist: The angle of rifling grooves relative to the bore axis. (Expressed as the distance in inches over which a turn or twist is completed, i.e., 1-10, 1-22.)

Velocity: The speed at which a projectile travels. (Usually measured in feet per second or metres per second.)

Wad: A disc used to separate powder from shot; or to seal propellant gases behind the shot; or to hold shot together in the barrel.

W.C.F: Abbreviation for Winchester Centre Fire.

Wheel-Lock: An early firearm mechanism in which a wheel with serrated edges is wound against the tension of a strong spring and spins against a piece of iron pyrite, sending a shower of sparks into the pan to ignite the charge.

Wildcat Cartridge: A non-standard cartridge usually made by modifying the shape of a standard cartridge.

Windage: The lateral drift of a bullet in flight caused by wind.

W.R.F.: Abbreviation for Winchester Rim Fire.

Zero: Sight adjustment so the bullet will strike the target at the point of aim.

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