NZGAC Hunter Education. Enabling better education and safer hunting practices.
NZ Hunter Education : Glossary Cont.
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
L
Lands: The spiraling raised portion of a bore remaining after the grooves have been cut or formed.
Lead Crusher: A pure lead cylinder used in a pressure gun for obtaining lead units of pressure (L.U.P. or lup). Formerly used to test low-pressure cartridges such as shotshells, this system is now obsolete in the US
Leade: See throat or freebore.
Leading: Lead deposited in the bore from the friction of lead bullets rubbing against the bore, or from gas-cutting of lead bullets. A form of metal fouling, some leading is normal; however, excessive leading can destroy accuracy and raise pressures.
Line of Departure: The line at which a bullet leaves the muzzle of a firearm, equivalent to the axis of the bore. The bullet immediately falls away from this imaginary line.
Line of Sight (LOS): The straight line through the sights of a gun to the point of aim.
Loading Block: A block of material, usually wood or plastic, with rows of holes to conveniently hold a number of cartridge cases during the loading operation. Especially useful when charging cases with a powder measure.
Loading Density: Ratio of the volume of powder charge to the volume of the case.
Locking Lugs: Usually used in reference to rotary bolt-action firearms. Protrusions on the bolt that engage a mating recess inside the receiver ring when the bolt is closed. This feature prevents the bolt from moving rearward when the rifle is fired.
Lock Time: The period of time between the release of the sear by trigger movement and the instant the priming mixture detonates after being hit by the firing pin.
Lubricant:
Lubricator-Sizer: A tool used to size and lubricate cast lead bullets. Often contracted to lubrisizer.
M
Magnum: Originally, a large wine bottle holding approximately 2/5 of a gallon. In shooting, it refers to a cartridge of exceptional size or power. First applied to large bottleneck cartridge, hence the name. Magnum is now more of a marketing term than a technical one.
Mean Radius (MR): The average radius of a group of shots from the center of the group. Another method of recording accuracy, MR is commonly seen in military contract specifications for accuracy. Extreme spread is more commonly used to measure accuracy in commercial ammo manufacturing and hobby shooting.
Meplat: The diameter of the flat or blunt end of the nose of a bullet.
Mercuric Primer: A primer in which the primary initiator is mercury fulminate. These primers have been obsolete since the advent of metallic cartridge reloading over a century ago. On firing, the compounds release minute amounts of metallic mercury. Mercury attacks the cartridge case making it brittle and thus unsuitable for further loading.
Metal Case (MC): Also Full Patched (FP) or Full Metal Jacketed (FMJ). A type of bullet in which the core is completely encased in jacket material, except for an opening on the base. Standard military bullet type.
Metal Fouling: Bullet jacket material deposited in bore due to friction. More common in very high-velocity rifle cartridge, metal fouling must be removed to prevent corrosion due to the electrolytic action of the copper against the steel barrel. Metal fouling can also result from a rough bore at any velocity.
Micrometer: A measuring instrument with a fine screw adjustment for measuring very small distances. Usually calibrated to read in increments of 0.001" or 0.0001".
Mid-range Trajectory (MRT): Usually refers to the highest vertical distance of a bullet above the line of sight at a point approximately halfway from muzzle to target or point of aim. The MRT is varies with the zero range for a given load. Also called the maximum ordinate.
Minute-of-angle (MOA): A unit of angular measurement equal to 1/60th of a degree. Although usually approximated as one inch per 100 yards horizontal distance, it is actually equal to 1.047" per 100 yards.
Misfire: Complete failure of a cartridge to discharge after the primer is struck by the firing pin.
Mushroom: The ability or capacity of a bullet to increase its diameter upon impact with animal tissue. The name comes from the desired shape after expansion.
Muzzle: The front end of a barrel. The point at which a projectile leaves the barrel.
Muzzle Blast: The pressure effect of powder gases jetting from the muzzle of a firearm.
Muzzle Brake: A deflector fitted to a gun muzzle to deflect exiting gases. Usually used to reduce recoil by redirecting the jet effect of muzzle blast. Also called a recoil compensator, or comp for short. See compensator.
Muzzle Energy (ME): The energy of a bullet at the muzzle. At this point a bullet's energy is highest. See energy.
Muzzle Pressure: Gas pressure in the barrel at the muzzle at the instant the bullet leaves the muzzle.
Muzzle Velocity (MV): See velocity.
N
Neck: That portion of a cartridge case that grips the bullet. In a bottlenecked case, that portion of the case in front of the shoulder.
Neck Down or Up: To change the diameter of the case neck during case forming to accept a larger or smaller diameter bullet.
Neck Expansion: The act of expanding a sized case neck by pulling it over an expander plug or button.
Neck Ream: Reducing neck wall thickness from the inside with a reamer. Commonly performed when forming a short case from a much longer one, such as the 300 H&H to 6.5mm Remington Magnum conversion.
Neck Size: To resize part or all of the neck only, leaving the case body unchanged.
Neck Turn: Reducing neck wall thickness from the outside by cutting or, more rarely, grinding.
Non-corrosive: Cartridges or primers with priming mixture that does not contain any compound capable of causing rusting or corrosion of bore or adjacent parts. All commercial small arms primers made in the US and most military ammunition produced since 1954 has non-corrosive primers, although it is well to clean the bore promptly when in doubt.
Non-mercuric: A priming mixture containing no mercury compounds.
O
Ogive: The curved portion of a bullet ahead of the cylindrical, or shank, section. Also, the radius of this curve, usually expressed in calibers.
Oil Dent: Dent in cartridge case formed by too much oil or lubricant when sizing. Usually seen on or near the shoulder.
Overbore Capacity: A common but unscientific term referring to a cartridge case that has too much case volume for its bore volume. Technically, every case can be over its bore capacity with some powder. Generally used when a case has a volume so large in relation to the bore diameter that only the very slow burning powders will give satisfactory performance.
P
Parallax: In telescopic sights, the condition that exists when the reticle (crosshairs) does not lie exactly on the image plane. Excessive parallax makes the shooter's eye position very critical if repeatable accuracy is to be obtained. Most lower power scopes have the parallax correction pre-set at 150 yards; high-magnification scopes (10X and up) commonly have an adjustable objective to correct for various distances.
Patched or Paper-patched Bullet: A bullet with a wrapped paper "patch" commonly used in older black powder cartridges. Derived from the even older cloth patch used to wrap a muzzle-loader ball. The patch helped seal the powder gases and reduced bore leading, and was an evolutionary step towards today's metal bullet jackets.
Pattern: The way a shotgun places its shot load. Generally measured as the percentage of pellets that strike in a 30" circle at 40 yards.
Pierced Primer: A primer that has been punctured; caused by a defective firing pin, a weak firing pin spring or excessive clearance between the firing pin and breech.
Plinking: Informal target practice commonly at informal targets. Shooting for fun where no one keeps score.
Point of Aim: That point on which a gun's sights are aligned so as to allow the bullet to strike the desired point of impact.
Port Pressure: In a gas-operated firearm, the pressure measured at the gas port leading to the piston assembly.
Powder: The propellant material used in most gun systems. Divided into two basic types: smokeless powder and black powder. It is produced in a wide variety of types, forms and brand names intended for specific applications. It varies chiefly according to burning speed. The fast-burning types are used for light bullets in short barrels at low velocities: slower-burning powders are used in longer barrels and in greater quantities to drive the bullet at higher velocities. Most powder contains a major percentage of nitrocellulose, with small traces of other compounds intended to control burning rate or prevent deterioration; such powder is called single-base; smokeless powders containing a percentage of nitroglycerin are called double-base. Powders containing substantial amounts of other organic nitrates are called mullet-base. Further identified by shape of individual kernels or granules. See ball powder, flake powder and extruded tubular powder. Black powder is a mechanical mixture of sulfur, charcoal, and saltpeter. It is now used primarily in muzzle-loading guns.
Powder Bridging: A "log jam" of powder that may occur in the drop tube of a powder measure. The powder kernels interlock and wedge together to block free passage. Most common with long, cylindrical powder kernels.
Powder Measure: A mechanical device to meter powder charges by volume. Used to speed the charging process, measures must be adjusted initially with an accurate scale.
Powder Scale: A sensitive measuring device used to accurately weigh small charges of powder. Designed expressly for cartridge reloading, it is usually graduated to permit weighing to units as small as 1/10th grain.
Powder Trickler: A mechanical accessory that dribbles a few powder granules at a time, used with a powder scale.
Pressure: The pressure exerted by a burning charge of powder in the chamber of a gun. Expressed normally as the peak pressure in pounds per square inch (psi) or copper units of pressure (cup) depending on the test equipment.
Pressure Gun: Device for measuring radial chamber pressure generated by a cartridge. Usually of the "crusher" type or of the electronic "transducer" type. Both types were used in the development of the Speer Reloading Manual.
Pressure-Velocity Ratio: Numerical comparison of velocity to pressure in a specific cartridge with given bullet and powder.
Primer: Also called "cap", deriving from the percussion caps used with some muzzle-loading arms. In a centre-fire cartridge, the small metal cup contains a detonating mixture that is used to ignite the propellant powder. The primer is seated in the primer pocket in the base of the cartridge case. The standard American type of primer, the "Boxer," also contains an anvil. Electrically fired primers are used in some military weapons and in some experimental sporting arms. In a rim-fire cartridge the priming mixture is contained within the rim of the case. See anvil, berdan, boxer, and battery cup.
Primer Flipper: A two-piece metal or plastic tray for orienting and turning primers. Facilitates loading of primer tubes in semi-automated equipment. Primer Indent: Depression made in primer by firing pin. Also called the firing pin impression.
Primer Leak: High-pressure gas escaping between the primer and primer pocket wall. Usually indicates a damaged primer pocket.
Primer Pocket: The vented cavity in the base of a centre-fire cartridge case made to receive and support the primer.
Primer Pocket Reaming or Swaging: Two methods for removing the primer pocket crimp from military cases. Reaming removes metal and swaging moves metal aside.
Primer Punch: A loading tool part that inserts the primer.
Primer Tool: A specialized tool that does only the priming operation. Usually used in reference to off-press priming.
Progressive: Characteristic of a powder that burns at a predictable rate compared to black powder, producing a relatively slow pressure build-up.
Projectile: A bullet or any other object projected by force and continuing in motion by its own inertia. Note: A bullet is not a projectile until it is in motion.
Proof Cartridge: A special cartridge used to test a new or repaired firearm for strength and safety. Usually about 25% higher pressure than normal maximum pressure. Not commercially available.
Propellant: The technically correct term for ballistic chemicals used to propel a projectile. See powder.
Protruding Primer: a) A fired primer that partially backs out of the primer pocket on firing. Usually an indication of low firing pressure. b) Any primer that is not fully seated below the case head.
Pyrodex®: A recently developed black powder replacement designed primarily for use in percussion muzzle loading arms, black powder cartridges and muzzle loading cannon. Manufactured and distributed exclusively by Hodgdon Powder Company.
Q
No item
R
Ram: The main plunger or shaft of a metallic ammunition-reloading tool.
Range:
1. A place where shooting is conducted.
2. The horizontal distance of travel of a projectile from gun to target.
Ream: To remove metal from a cavity with a rotary cutting tool.
Rebated Rim: In cartridge case design, a case whose rim is smaller than its body. Examples: 284 Winchester and 41 Action Express.
Recoil: The backward thrust or "kick" of a gun caused by the powder gases pushing the bullet through the bore and the jet effect of the gases themselves.
Recoil Buffer: A cushioning device to help reduce action battering; most commonly used to limit bolt travel in semi-automatic firearms.
Reloading Press: A tool used in reloading ammunition. Usually has some form of mechanical advantage to reduce effort in resizing or reforming cases. Hold components in precise alignment. Available in several basic types known by the shape of letters of the alphabet; "O" types are most common today, but "H" and "C" types have also been used.
Remaining Energy: The residual or "down-range" energy of a projectile, measured in foot-pounds, at a given distance from the muzzle.
Remaining Velocity: The residual speed of a projectile at a given point on its trajectory.
Reticle: The aiming indicator at the focus of a telescopic sight. May consist of straight or tapered lines (crosshairs), dots, posts, or some combination thereof. Some scopes have auxiliary marks for range estimation.
Rifling: Spiral grooves cut or impressed into the bore of rifles and pistols in order to make the bullets spin, insuring stable flight to the target. See grooves and lands.
Rim: The feature at the base of most cartridge cases in which the extractor engages to pull a fired cartridge from the chamber. In England this is called the flange. See rimless and rimmed.
Rim-fire (RF): Cartridges that contain the priming mixture within the rim. This type is not reloadable under any practical conditions.
Rimless: A case head type; actually a misnomer. Rimless cases have a rim, but it is the same diameter as the case body so it does not protrude.
Rimmed: A case head type whose rim protrudes beyond the case body. Example: 30-30 Winchester.
Round: A military term meaning one complete cartridge. Round Nose: Bullet design feature; a blunt, spherical nose shape.
Rupture: Also separation. In shooting, a failure or break in the wall of a cartridge case, usually allowing gas to escape.
S
SAAMI: Small Arms and Ammunition Manufacturers Institute. The organization that establishes firearms standards in the United States.
Sabot: From French for "shoe." In modern small arms usage, a lightweight carrier or "shoe" in which a sub-caliber projectile is centered to permit firing the bullet in a larger caliber barrel. Sabots are usually the discarding type; they fall away from the bullet soon after exiting the gun barrel. Pronounced "say-bo."
Seating Depth: In a loaded cartridge, the depth to which the base of the bullet is seated below the case mouth.
Sectional Density: A bullet's weight in pounds divided by the square of its diameter in inches.
Shank: The cylindrical section of a bullet below the ogive. The shank usually defines the bearing surface, that is, the portion of the bullet that contacts the barrel.
Shell Holder: The part of a reloading press that holds the head of the cartridge case on the ram permitting insertion and withdrawal of the case from the loading dies.
Shock: See hydrostatic shock.
Shock Wave: The compression wave formed whenever the speed of a projectile relative to air or other medium exceeds that at which the medium can transmit sound.
Shot: Lead alloy spheres, sometimes copper or nickel-plated, used for the projectiles in shotguns. Chilled shot is hardened. Drop shot is very soft.
Shoulder: The sloping or rounded part of a bottleneck cartridge case between the neck and the body.
Sighting in: Firing a rifle or pistol to determine its point of impact at a specified range and adjusting the sights so the point of impact has the desired location with regard to the point of aim.
Single-base Powder: Nitrocellulose powder made without the addition of any other highly nitrated chemical such as nitroglycerin. See double base powder.
Sizing: Also resizing. Reducing a fired cartridge case to dimensions that allow easy chambering in a firearm of the appropriate caliber. May be full length, partial, or neck sizing. Cast lead bullets are also sized or reduced in diameter by forcing through a die.
Slug: A large, single projectile, often bearing external pre-cut rifling, intended for adapting shotguns to the hunting of larger game such as deer. Also a slang term for bullet. As a verb, "to slug" means forcing a soft lead slug through the bore of a gun and measuring it to determine barrel dimensions.
Smokeless Powder: A nitrocellulose-based propellant. Leaves a non-corrosive residue, but normally produce small amounts of smoke. Named because smoke production is very small compared to the older black powder.
Soft point (SP): Bullet design feature in which a portion of the lead alloy core is exposed at the tip of a jacketed bullet to permit the bullet to increase its diameter upon impact with tissue.
Spent: In shooting, a cartridge or component thereof that has been fired.
Spherical Powder: A registered trademark of Hodgdon Powder Company use to describe round or semi-round grained powders. See ball powder.
Spin: The rapid rotation of the projectile caused by the spiral rifling of the bore. At the muzzle of a high-velocity rifle, spin can be in excess of 300,000 revolutions per minute.
Spire Point: A conical pointed bullet. The line from the shank to the point is nearly straight.
Spitzer: Bullet design feature from German for "point". A bullet with a pointed nose. The line from the shank to the tip is arched. Compare to spire point above.
Stabilize: To spin a projectile around its long axis rapidly enough to keep it point-on in flight.
Swage: To form by forcing into or through a die. Rhymes with "age."
T
Throat: That area of the bore immediately ahead of the chamber tapering to the point where the rifling starts. See also leade or freebore.
Time of Flight (TOF): The elapsed time, in seconds, of a bullet's flight from muzzle to a given point down-range.
Trajectory: The path of the projectile in flight relative to the line of sight.
Transducer: In ammunition research, a piezoelectric device made of quartz that develops a voltage directly proportional to the pressure applied to it. Used to measure chamber pressures.
Twist: The rate or angle of the rifling in relation to the axis of the bore. Usually measured by the length of barrel required to rotate a bullet one complete turn.
U
Usage:
1. The tendency for a bullet to become more cylindrical on firing due to inertia. Also known as slugging.
2. The expansion on impact of a hunting bullet. See mushroom.
V
Varmint: A variation of "vermin." A wild animal or bird considered a pest, usually not covered by game regulations.
Velocity: The speed of a projectile. Usually measured in feet per second (fps) at a given range.
Vernier Caliper: A simple slide-type precision measuring tool used by hand loaders. "Vernier" refers to the readout mechanism. The dial-type and electronic digital caliper are becoming more popular because they permit faster and less error-prone readings
W
Wad: A disc of paper, felt, cork, plastic or other material used primarily in shot shells to separate powder from shot. Can be over-powder, filler, cushion or a combination of these. Speer shot capsules for handguns feature a wad to seal the bore.
Wadcutter: A cylindrical, sharp-shouldered handgun bullet designed to cut a clean round hole in a paper target for maximum score in competition.
WCF: Winchester Center Fire. A proprietary name applied to several cartridges developed by Winchester
Web: That part of a cartridge case between the bottom of the primer pocket and the interior of the case. The web is pierced by the flash hole.
Wildcat: A cartridge formed by altering an existing commercial case to make a style that is not available from ammunition companies. SAAMI dimensional and pressure standards do not apply to wildcat cartridges.
Windage: The amount of sight correction, left or right, applied to compensate for natural drift and/or wind deflection of a projectile.
Wind Deflection: Lateral change in the path of a projectile due to crosswind effects.
Work-hardening: The change in hardness of metal due to repeated flexing or stress. In reloading, continued sizing of a case can work-harden the metal until cracks appear. See annealing.
Working-up:
1. The process of developing a safe maximum load by starting with a lower powder charge and increasing it in small steps only after firing and checking for signs of pressure at each point along the way.
2. Accuracy testing of known safe loads in a step-wise manner.
X
No item
Y
Yaw: A situation where a bullet “wobbles” on its axis at a small angle to the line of flight. In yaw, a bullet's tip is normally on the axis of the path but the base is spiraling around that axis. The spin of the bullet causes it to settle into stable flight with both tip and base on the same path axis, usually within 40 to 100 yards for a rifle.
Z
Zero: More correctly, "Zero Sight Adjustment." That adjustment of a gun's sights that will place a properly aimed shot at the desired point of impact at some range with a given load, in the absence of wind. The basis from which subsequent sight adjustments are made.
Zero Range: The distance at which the bullet path exactly coincides with the line of sight (LOS). Each gun/load combination actually has two zero ranges—one near the muzzle as the bullet rises through the LOS and another at some greater distance where the bullet descends through the LOS. Normally, it is the second zero range that most shooters need to know.