NZGAC Hunter Education. Enabling better education and safer hunting practices.
NZ Hunter Education : Glossary
INDEX
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
Accuracy: The measure of precision in consistently obtaining a desired result. In shooting, the measure of a bullet or gun’s ability to place all shots close to the same point.
Action: The mechanism of a firearm by which it is loaded, locked, fired and unloaded.
Air Resistance: The slowing effect of air on a projectile in flight.
Anvil: In the priming system, a fixed metallic point against which the priming mixture is crushed and thereby detonated by the action of the firing pin.
B
Ball: Early term for "bullet." Still used in military nomenclature, usually to describe a full-metal jacketed bullet.
Ball Powder: Trademarked name for a double base smokeless propellant powder developed by Olin, Inc. Either spherical or flattened spherical shape.
Ballistics: The science of projectiles in motion. Divided into three categories: interior ballistics—covering the time between the start of primer ignition and the bullet's exit from the barrel; exterior ballistics—the bullet's movement from barrel exit to target impact; and terminal ballistics —the bullet's behavior from the moment it enters its target until it stops moving.
Ballistic Coefficient (BC): Ratio of the sectional density of a bullet to its coefficient of form. Represents the projectile's ability to overcome the resistance of the air in flight; a bullet with a high BC will overcome air resistance better than one with a low BC.
Battery Cup: Type of primer in which anvil and primer cup are supported in an outside cup. Shot shell primers are of this type.
Bearing Surface: That portion of a bullet's surface that touches the bore in moving through the barrel.
Bedding: Manner in which the barrel and action of a rifle is fitted to the stock.
Bell: To expand the mouth of a case slightly in order to seat a bullet more easily. Also called flare.
Belted Case: Case head type with raised band or belt at the base ahead of extractor groove. A variant of the rimless case. Belt acts to control headspace of the cartridge. See rim and rimless.
Berdan: Type of primer common outside the US with no integral anvil. Anvil is formed in bottom of primer pocket in the case. Named after the inventor, Col. Hiram Berdan, an American.
Bench Rest: A solid table or bench used for supporting a gun when testing for accuracy. Bench Rest target shooting has become an important shooting sport where the smallest group wins.
Black Powder: The oldest ballistic propellant for muzzleloaders and early cartridge arms composed of a mixture of potassium nitrate (saltpeter), charcoal and sulfur.
Boat Tail: Name given to a bullet type with tapered base. Also called “tapered heel,” the design reduces aerodynamic drag on the bullet by smoothing the airflow over the base.
Body (of a case): That section of a cartridge case between the head and the shoulder that contains the powder.
Bolt: The locking and cartridge-supporting mechanism of a firearm that operates in line with the axis of the bore. It contains the firing pin, firing pin spring, extractor(s) and sometimes the ejector.
Bullet: The missile only. Becomes a projectile when in flight. Not to be applied to the term cartridge. See also ball.
Bullet Path: The track followed by a bullet in flight. It is described by the location of the projectile above (+) or below (– the line-of sight at a given range.
Bullet Pull: The amount of force needed to extract a bullet from a loaded cartridge. Used by ammunition manufacturers to measure uniformity of crimp and/or case neck tension.
Bullet Puller: A tool for extracting bullets from loaded centrefire cartridges. The inertial and collet types are most common. Used to correct loading errors or salvage components from ammunition that is unsuitable for firing.
Burning Rate: A relative term used to rank the rapidity with which a given powder releases energy in comparison with other powders. Typically based on heat generation in a lab device called a calorimeter bomb. In a real-world gun system, burning rates may vary depending on factors such as case size, pressure range, expansion ratio, and others.
C
Calibre: A term derived from Arabic qalib, meaning "mould" or “form,” first applied to the weight of a bullet and then to the diameter. Calibre now refers specifically to the diameter of either a projectile or the bore of a gun. It is the approximate diameter expressed (in English) in hundredths of an inch. A bullet that is 0.451" in diameter is 45 caliber. To write ".30 caliber" is technically incorrect. According to the strict definition, such a bullet would only be 0.003" in diameter! Also used in naval artillery as a measure of bore length compared to the diameter (or caliber) of a specified gun. A "five-inch, fifty-four caliber" naval rifle would have a barrel 270 inches or 22.5 feet long.
Cannelure: Circumferential groove(s) around a bullet or cartridge case. Used for identification, to hold lubricant, or to crimp case into.
Canister Powder: Since hand loaders do not have the laboratory facilities needed to determine the loading characteristics of a powder, powder manufacturers have developed a rigid set of specifications for each hand loader powder they sell. Each lot of powder is made or blended to meet these specifications so the hand loader will always have uniform results. Powder made to these specifications is termed "canister" grade since it is usually packed in canisters of appropriate size for consumer use. Commercial ammunition manufacturers that have laboratory facilities can use the "bulk" grades, which may vary enough from lot to lot to be dangerous to hand loaders. Loads are adjusted for each powder lot as required by test results.
Cap: See primer.
Cartridge: A complete unit of assembled ammunition: case, propellant powder, primer, and bullet. Commonly applied only to rifle and pistol ammunition, but occasionally to shot shells.
Case: The paper, metal, or plastic container that holds all the other components of a cartridge. Sometimes called hull or shell.
Case Forming: To alter or modify one cartridge case to another of different shape and or caliber. Also see wildcat.
Case Trimming: Shortening an overly long case by removing metal at the case mouth.
Cast Bullet: Bullets for rifles or pistols formed from molten lead or lead alloy in a mould. See mould blocks.
Center Fire (CF): Refers to centrally located primer in base of metallic cartridges. Also called centre fire. Most centre fire cartridges are reloadable.
Chamber: That part of the bore, at the breech, formed to accept, support, and confine the cartridge. In a revolver, chambers are located in the cylinder.
Chamber Cast: A casting, usually of molten sulfur or low melting-point metal poured in the chamber, to assess chamber shape, dimensions, or condition.
Chamfer: To bevel or ream a taper on the inside of a case mouth to facilitate bullet seating.
Charge: The amount of propellant powder measured into the case in loading. Also refers to amount of shot measured into shot shell.
Choke: A constriction at the muzzle of a shotgun barrel designed to control the spread, or dispersion, of the shot charge.
Chronograph: A mechanical or electronic device used to measure the velocity of a projectile.
Collimator: In shooting, an optical device used to align the sights with the bore of a rifle or handgun.
Combustion: Burning; in firearms, the chemical process which unites oxygen and other substances in gunpowder to release energy in the form of heat and gas. Also called deflagration.
Compensator: A device fitted to the muzzle of a firearm to reduce recoil or muzzle rotation. Usually applied to such devices when fitted to a handgun. See muzzle brake.
Compressed Charge: A charge of powder that is compressed by the bullet during seating in the case.
Components: The parts that go into the making of a cartridge.
Copper Crusher: Small, solid copper cylinder used in a pressure gun to measure chamber pressure. See pressure gun.
Core: The interior part of a jacketed bullet; usually a lead alloy in sporting ammunition.
Cordite: Trade name for a long, tubular-grained, double-base powder used mainly in Great Britain, and one of the earliest smokeless propellants. The granules are often as long as the powder space.
Corrosion: The eating away of the bore because of rusting or the chemical action of salts deposited in the bore by corrosive primers or powders. See below. Cartridge cases can also be corroded by salts or acids.
Corrosive Primer: A primer whose burnt residue is hygroscopic (attracts moisture) and usually containing slats of chlorine. The residue will rapidly rust a bore unless removed. All component primers in the US have been non-corrosive for decades
Crimp: The bending inward of the mouth of the case in order to grip the bullet, or to close the mouth of a shot shell case. Two types are used. A roll crimp is the bending or folding the mouth of the case into the crimp groove or cannelure of the bullet. In a taper crimp, the mouth of the case is pressed into the bullet body without folding the case mouth.
Crimped Primer: A forcing inward of the brass around the top of the primer pocket to prevent setback of primers. This is usually found on military cartridges intended for use in fully automatic weapons. Unless the crimp is removed after depriming—either by swaging or reaming—priming of the case is very difficult.
Cupro-Nickel: A copper-nickel alloy once used extensively for bullet jackets. It was largely replaced by gilding metal because of barrel fouling problems.
D
Damascus barrels: Barrel tubes built up by twisting alternate strips of iron and steel around a fixed rod (mandrel) and forge-welding them together in varying combinations according to the intended quality and the skill of the maker. The rod was withdrawn, the interior reamed and the exterior draw-filed until the finished tube was achieved. Damascus barrels may be recognized by any of a variety of twist or spiral patterns visible in the surface of the steel. Generally unsafe to use with modern smokeless powders – check with a gunsmith first before using.
Deburr: To remove burrs or roughness sometimes left on case mouth edge by trimming operation. See chamfer.
Decap or Deprime: To remove or eject a primer from its primer pocket. Usually done by the decapping pin in the sizing or expanding operation.
Deterrent Coating: A chemical coating applied over powder kernels to control the burning characteristics of the base powder. Aptly described as a "temporary fire-proofing" of a powder kernel.
Die: In hand loading, a tool to form or reform cases or bullets, or to seat bullets.
Double-base Powder: Nitrocellulose (smokeless) propellant that uses nitroglycerin as the plastisizer.
Drag: See air resistance.
Dram Equivalent: In shot shells, a term used to indicate that a charge of smokeless powder produces the same velocity as a given number of drams of black powder. Thus, a 3 dram equivalent load has a charge of smokeless powder that gives the same velocity as a similar load charged with 3 drams of black powder. One dram equals 27.3 grains.
Drift: In exterior ballistics, the deviation of a projectile from the line of departure due to its rotation or spin. Also commonly applied to the effects of wind. See wind deflection.
Drop: The distance a projectile falls due to gravity, measured or calculated from the line of departure. Must be corrected for difference between line of sight and line of departure. Drop is normally reported assuming a horizontal barrel.
Duplex Load: Use of two different powders in loading the same cartridge. There is little or no advantage to duplex loading in small arms and results are unpredictable and usually dangerous.
E
Elevation: The vertical adjustment of a sight to bring the point of aim to coincide with the point of impact.
Energy: The amount of work capable of being done by a projectile at a given range, expressed in foot-pounds in the English system. Found by multiplying the square of the velocity in feet/sec by the weight of the bullet in grains and dividing by 450,400.
Engraving: The marks made on the bullet by the rifling.
Erosion: The wearing away of the bore of a firearm due to friction from the projectile combined with the action of hot powder gases.
Expander Ball or Button: The round steel part of a die that expands the sized neck of a cartridge case to the diameter needed to hold the bullet firmly.
Expansion Ratio: Ratio of interior case volume to bore volume.
Extruded Primer: A primer that, on firing, has the metal of the primer cup forced back into the firing pin hole in the face of the bolt. Also known as cratering. Usually a gun problem rather than a pressure sign.
Extrusion: The shaping process used in the manufacture of bullet jackets and cores.
Extruded Tubular Powder: Another term for cylindrical powder. Formed by forcing damp propellant mix through a die during manufacture and cutting to desired lengths. May have one or more longitudinal holes through the grains.
F
Fire form: Using the pressure of normal firing to shape a cartridge case to fit a given chamber.
Firing Pin: That part of a gun's mechanism that strikes the primer to start ignition.
Flake Powder: A smokeless powder characterized by thin, disc-shaped granules.
Flash Hole: The hole leading from the primer pocket into the body of the cartridge case. Also called the vent.
FMJ: Full metal jacket. See metal case.
Foot-pound: A unit of kinetic energy in the English system defined as the effort required to vertically lift one pound a distance of one foot against the force of gravity.
Forcing Cone: The slope of the forward end of the chamber of a rifle or shotgun that decreases the chamber diameter to bore diameter.
Form Factor: A multiplier that relates the shape of a bullet to the shape of the standard projectile used to determine the ballistic coefficient.
FPS: Feet per second, a measure of velocity in the English system. Also feet/sec, ft/sec, or fs.
Freebore: The distance, if any, that a bullet travels upon firing before it contacts the rear portion or origin of the rifling.
Frontal Ignition: Experimental type of cartridge where primer flash is directed to the forward part of the powder charge through a metal tube.
G
Galling: Effect of friction between a cartridge case and sizing die, producing roughness on the case and case metal deposited on the die surface.
Gas: In handloading, the vapor produced by burning powder. This heavy gas is capable of expanding rapidly, creating sufficient energy to propel the bullet at high speed.
Gas Check: A copper or brass cup used to prevent hot, high-pressure powder gases from deforming the base of lead bullets.
Gilding Metal: A copper-zinc alloy used for bullet jackets, consisting of 5 parts zinc and 95 parts copper. Commercial bronze (10 parts zinc to 90 parts copper) is informally referred to as gilding metal when used for bullet jackets.
Grain: In English weight measure, 7000 grains equal one pound; 437.5 grains equal one ounce. Incorrectly used in referring to a particle, or kernel, of powder. Thus "35 grains of powder" always refers to 35 of the weight-unit grains, never to 35 individual kernels of powder.
Grand Slam: An honorary award to a hunter who has collected the four varieties of North American wild sheep. Also the registered trademark of the premium hunting bullet made by Speer.
Granulation: Refers to powder grain size and type. Can apply to either black or smokeless powder.
Grease Groove: Lubricating groove. On a lead bullet, a circumferential groove used to hold lubricant.
Grooves: Spiral cuts or impressions in the bore of a firearm that cause a bullet to spin as it moves through the barrel. See rifling.
Group: The pattern made at the target by a number of shots fired with one aiming point and usually one sight setting. Usually measured from center to center of the holes farthest from each other.
Gun Powder: Propellant explosive used in small arms. Can be either smokeless or black powder.
H
Half-jacket: A short jacket or a bullet swaged with a short jacket, which leaves some lead in contact with the bore. A three-quarter jacket is similar but longer, so the bearing surface of the bullet is covered by the jacket material.
Hang fire: Slang term for a delayed firing, which is any detectable delay in the ignition of a cartridge after pulling the trigger. Can be a chemical delay caused by the cartridge, or a mechanical delay caused by a defect in the firearm. Chemical delays are recognized as being less that 0.3 seconds. The use of modern lead styphnate priming has virtually eliminated the chemical delay. Chemical delays were more common with the now obsolete potassium chlorate priming compounds.
Headspace: The distance from that surface of the barrel or chamber that prevents the cartridge from moving further forward into the chamber, to the face of the breech with the action fully closed and locked. This is the most important dimension governing the safety of the shooter. In hand loading, the combination of cartridge case and gun must be considered when talking of headspace. To a hand loader, few guns need to have excessive headspace, since he can adjust the cartridge case to fit the chamber, even though the chamber may have excessive headspace when measured by SAAMI standards.
Heel: The edge of the bullet base.
Holdover: The distance above target a shooter must "hold over" to hit at ranges greater than the gun's "zero." See zero.
Hollow Point (HP): Bullet design feature; an axial hole at the point of the bullet.
HOT-COR: The registered trademark for Speer's exclusive process of manufacturing flat-base rifle bullets. A molten core is poured into a clinically clean jacket and then the bullet is immediately swaged to shape, with a resulting tight bond between core and jacket.
Hydrostatic Shock: A pressure wave created by a bullet passing through animal tissue, which is high in water content.
I
Ignition: The setting on fire of the propellant powder charge by the primer.
IHMSA: International Handgun Metallic Silhouette Association.
Improved: Term used to indicate a standard cartridge case that has been altered by fire forming to reduce body taper and/or increase shoulder angle. Improved cases have greater powder capacity than the corresponding standard case.
IMR: Abbreviation for "Improved Military Rifle," a trademark of DuPont (now IMR Powder Company) to its line of single-base rifle powders. Ingalls' Tables: Ballistic tables computed by Col. James M. Ingalls and first published in 1918. The most widely used ballistic tables in the US.
IPSC: International Practical Shooting Confederation.
J
Jacket: The cover or "skin" of a bullet. Usually made of gilding metal in the US, but copper-clad steel and mild steel are also used in other countries. See cupro-nickel and half-jacket.
K
Keyhole: The imprint of a bullet on a target that shows that the bullet was not traveling point-on at the time of impact.