Glossary Of TermsA Accuracy: The measure of precision in consistently getting the desired results (small groups),in shooting, the measure of the bullet’s or rifle's ability to place all shots close together, at the same point of aim on the target.
Action: The working mechanism of a rifle by which it is loaded, locked, fired and unloaded. Ammunition - the assembled components of complete cartridges or rounds, necessary for loading and firing a firearm. The case or brass holding a primer, a charge of propellant (gunpowder) and the projectile (bullet). Also called “ammo”, or "bullets".
B
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: (abbreviated as BC) The projectile's (bullet's) ability to overcome the resistance to air in flight(drag); a bullet with a high BC will overcome air resistance better than one with a low BC.
Bench rest: (1.) A solid, heavy table (usually made of heavy iron and cement) from which a rifle is rested and fired. (2.) A target competition where a group of marksmen shoot a number of bullets into the smallest hole, or smallest group of holes.
Bedding: (also called glass bedding) Fitting the metal parts of rifle (action and barrel) to a quality wood or fiberglass stock, using a fiberglass-epoxy resin combination and, in some instances, steel pillars. This process gives the barrel, action, and stock stability, consistency, and accuracy when shooting. Black Powder: An explosive propellant composed of potassium nitrate, charcoal, and sulfur.Black Powder: The oldest ballistic propellant for muzzle loaders and early cartridge arms composed of a mixture of potassium nitrate (saltpeter), charcoal and sulfur. Boat Tail: The tapered section between a bullet's bearing surface and base, intended to reduce the effects of drag by smooting the air flow over the base. The bullet has a higher ballistic coefficient than a comparable flat-based bullet. Bolt: The part of a rifle's action that contains the firing pin, firing pin spring, and extractor mechanism. This locking and cartridge-supporting mechanism operates in line with the axis of the bore.
Bore - The interior portion of a rifle's barrel excluding the chamber. In a rifled barrel, the bore diameter is the measurement from the top of one land, to the top of the opposing land. Bore Guide: A tool used during the cleaning process that keeps the cleaning rod centered in the bore, reducing the chance of damage to the throat, bore, and crown of the rifle barrel.
Bore Sight: To bring the sights into rough alignment with the bore visually, or with a collimator. Bore sighting is done in preparation for sighting in your rifle. Brass: An alloy of copper and zinc of which cartridge cases are usually made. slang term applied to empty cartridge cases. Bullet: projectile when in flight,fired from a rifle. Made of many materials, consisting of many shapes,weights, and constructs; in rifles lead with a copper jacket, ballistic-tip, soft-point(lead), hollow-pointed, etc.
Bullet Path: The vertical distance, normally expressed in inches, above or below a firearm or scope's line of sight. The path followed by a bullet in its flight to a target.
Bullet Puller: A collet or inertial type tool used to extract a bullet from a case or loaded cartridge, used to break down ammunition, correct loading errors, and salvage components from ammunition which would be unsafe to fire.
Bumped - Slang for being detected and accidentally flushing game animals by getting too close, being seen, smelled, heard. "Getting busted" by the animal, or "Blowing the stalk". Burning Rate: A term used to rank the relative quickness of different powders to release their energy, as compared to the known standard. Burning rate is extremely important in determining a powder's suitability for the cartridge being used. buring rates can vary depending on factors such as case size, amount of powder used, expansion rate, pressure range, etc. Bushing Die: A sizing die, neck or full length, in which the neck tension is controlled by using any of a series of interchangeable bushings to control the outside diameter of the resized case neck. These bushings are available in increments of .001" to provide virtually infinite control over the resizing process.
C Caliber refers to the diameter of either the projectile (bullet) or the bore of a rifled firearm or the diameter between lands in a rifled barrel. Caliper: A measuring instrument consisting of adjustable jaws used to determine thickness, diameter or length. An essential tool for the handloader.
Cape - The hide covering the head, neck, and shoulders, of a game animal, removed from carcass by skinning, and used for mounting as a trophy by a taxidermist.
Cartridge: A single, complete round of ammunition. Modern cartridges comprise: 1) brass 2) a bullet, 3) a primer, and 4) the powder (propellant) charge.
Case Trimmer: A tool for cutting cases back to length after being stretched by firing or reforming. Case Trimming: Shortening an overly long case by removing metal at the case mouth. Centerfire - Ammunition/cartridge with its primer located in the center of the base of the case. Chamber: The rear area of a firearm into which the cartridge is loaded in preparation for firing, and which supports the cartridge during firing.
Chamfer: To remove burrs on the inside of the case mouth by cutting a slight bevel or taper. Chamfering reduces the possibility of damage to the case, by making the bullet seating process easier.
Charge: The specified amount of a particular powder loaded into a case. The act of putting powder into a case. The amount of propellant powder measured into the case in loading.
Chronograph: An instrument used in determining the velocity of a projectile. Most are based on the time taken by a projectile to traverse a known distance between two points. Collimator: In reference to firearms, a collimator is an optical device used to “bore sight” a rifle or handgun. In use, a pilot, or spud, is inserted into the muzzle and the sights are aligned by means of a screen attached to the spud. While this may be done as the first step in “zeroing” a gun, it should never replace actual shooting and confirming at the range.
Compass: An instrument or device for determining directions, by means of a freely rotating magnetized needle that indicates magnetic north.
Compensator: A type of muzzle brake which diverts powder gases to reduce the recoil.
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.
Crown: The point of the bore where the rifling terminates at the muzzle. Cryogenic Process - A method of stress relieving steel by subjecting it to extreme temperatures. When performed on rifle barrels, the steel molecules are re-aligned to help reduce the stresses imparted to a barrel during machining. In addition, the bore of a cryogenic treated barrel is smoother and harder - making it less prone to copper fouling and easier to clean. The life of the cryogenic treated barrel will be increased by as much as 1/3 more barrel life.
D
Deburr: To remove burrs and roughness around the inside and outside of a case mouth. Burrs are a normal byproduct of case trimming, and must be removed before reloading the case.
Decap or Deprime: To remove or eject a spent primer from its primer pocket. Usually done by the decapping pin in the sizing or expanding operation.
Dies: In reloading, the tooling by which the resizing, reforming, case neck expanding, bullet seating, operations are performed. Used in conjunction with the reloading press. 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. Normally measured in inches at any given range.
E
Elevation: The vertical adjustment of a sight to bring the point of aim into coincidence with the point of impact.
Energy: The amount of work capable of being done by a projectile at a given range. In ballistics, kinetic energy is normally expressed in units of “foot-pounds.” One foot-pound is equivalent to the energy required to lift one pound one foot against the force of gravity. Erosion: The wearing away of the throat area the barrel due to friction from the projectile combined with extreme heat and hot gasses. Erosion occurs in all firearms but is aggravated by rapid fire, large case capacity, and the use of hotter burning powders.
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. In dies for bottlenecked cases, the expander is found on the decapping stem.
Exterior Ballistics: The branch of ballistics which deals with the projectiles flight, from the time it leaves the muzzle, until it impacts on target.
F
Firing line: A line parallel to the targets, from behind which firearms are discharged. Firing Range: (1) A facility designed for the purpose of providing a place on which to discharge firearms, shoot air guns and archery equipment.
Firing Pin: Also called the striker, That part of the firearm which strikes the primer, causing ignition. Flash Hole: The hole leading from the primer pocket into the body of the cartridge case. Fluting: The cutting of grooves length wise on a rifle barrel to aid in cooling of the barrel during firing. Also gives an integral stiffness to the barrel that enhances accuracy.
FPS: Abbreviation for “Feet Per Second”, usually in reference to the speed of a given projectile (bullet). Also feet/sec.
Fireform: Using the pressure of normal firing to shape a cartridge case to fit a given chamber.
Flash Hole: The hole leading from the primer pocket into the body of the cartridge case. Also called the vent.
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.
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: The rapidly expanding vapor,produced by burning powder, causes combustion. As the gas expands in an enclosed chamber (the cartridge case), it generates tremendous pressure. It is this pressure which drives or propels the projectile at high speed to the target.
Glassing: The art of spotting and locating game animals through the use of binoculars and spotting scopes on a tripod. Global Positioning Satellite (GPS) and Device: An electronic device that is battery powered, that will enable the user to link up and track 12 or more navigational satellites in outer space giving the user their real time position or location on the earth's surface. When used in conjunction with compass, and map, can greatly increase the Outdoorsman from getting lost. Grain: A unit of weight equaling 1/7,000th of a pound. The most common unit of weight measurement for the handloader; bullets are measured in grains, as are charge weights of powder. There are 7,000 grains in a pound, 437.5 grains in one ounce.
Greenhill Formula: A mathematical formula developed by Sir Alfred Greenhill to determine the twist necessary to stabilize an elongated bullet. The Greenhill formula states, the twist required (in calibers) equals 150 divided by the length of the bullet (in calibers).
Grooves: The area between the lands in the bore of a rifled firearm. The grooves are cut or impressed into the surface of the bore, and serve to impart spin to the projectile. Spiral cuts or impressions in the bore of a firearm which cause a bullet to spin as it moves through the barrel. See rifling.
Group: The pattern formed by a series of shots on a target, fired generally using the same aiming point, from the same range. Group size is used to determine a firearms accuracy potential. The most common way to measure is from center to center of the holes farthest from each other. Gunpowder - Chemical substances of various compositions, particle sizes, shapes and colors that, on ignition, serve as a propellant. H
Handloading: The practice of loading or reloading small arms ammunition by hand-powered equipment and methods. The process of putting a fresh primer, powder charge, and bullet into a used brass cartridge case (the most expensive part).
Hangfire: Slang term for a delayed firing of a bullet,sometimes quite noticeable, any detectable delay in the ignition of a cartridge after pulling the trigger. Usually a mechanical delay caused by a defect in the firearm or in the primer of a cartridge. Head: As applied to cartridges, the base area of the case. This area encompasses the primer pocket, extractor groove, and the rim or belt, extending up to the body of the case. Head Separation: A circumferential cracking around the body of the case, usually just above the web area. A complete head separation will normally leave the forward portion of the case in the chamber upon extraction. Generally caused by excessive headspace. Headspace: The amount of play between the case head and the breech face, in a fully closed action. This is an important consideration concerning safety to the shooter. Insufficient headspace will cause difficulty in chambering, while excessive headspace will result in head separations. Headspace problems may be the fault of the rifle, ammunition, or a combination of both. Head Stamp: A series of letters, numbers, or characters stamped into the head of a cartridge case to denote caliber, type, manufacturer, date of production or other pertinent information. High Primer: A primer which has not been fully seated in the primer pocket, and extends slightly above the head of the case. High primers can be a dangerous defect, and can result in slam fires. This is especially true in autoloading firearms.
Hold-over: The distance above target a shooter must "hold over" to hit at ranges greater than the gun's "zero." If used this type of practice must be done exactly, with all hold-over distances verified for accuracy.
I Ignition: The setting on fire of the propellant powder charge by the primer.
Improved: Term used to indicate a standard cartridge case which has been altered by fireforming to reduce body taper and/or increase shoulder angle. Improved cases have greater powder capacity than the corresponding standard case. Interior Ballistics: The branch of ballistics dealing with events occurring between the detonation of the primer and the projectile leaving the muzzle.
J
Jacket: The "skin" or outer sheath, covering the interior portion (core) of a bullet. Many different materials, including steel, have been used in making jackets, but today, 95/5 gilding metal is the industry standard.
L
Land(s): The raised portions of bore extending above the grooves in a rifled barrel.Lands: The spiraling raised portion of a bore remaining after the grooves have been cut or formed.
Line of Sight: A imaginary straight line passing through the sights of a firearm to the target, or point of aim. Load Density: The weight of the powder charge in grains, divided by the volume (frequently expressed in grains of water) of the case. Ratio of the volume of powder charge to the volume of the case. Locking Lug(s): The protruding lug(s) which engage the receiver to lock the action closed during firing. Locking lugs are normally situated on a firearms bolt. This feature prevents the bolt from moving rearward when the rifle is fired. Lock Time: The time interval between the sear’s release of the striker or firing pin, and the subsequent impact on the primer.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: Any substance used to reduce friction. Specific types are used for firearm mechanisms, cast bullets, or case resizing.
M
Metal Fouling: Metallic, bullet jacket residue left in a barrel after firing. This fouling, leaves copper build up in the bore, and will have a detrimental effect on accuracy. More common in high-velocity rifle cartridges, due to the friction.
Minute Of Angle: (MOA) A unit of angular measurement equaling 1/60th of a degree. One minute of angle works out very close to one inch at hundred yards, making a convenient measurement for shooters to use in describing accuracy. One minute of angle = 1.047" @ 100 yards.
Misfire: Complete failure of a cartridge to discharge after the primer is struck by the firing pin. Also referred to as hangfire.
Mushroom: The ability or capacity of a bullet to penetrate, expand, and increase its diameter upon impact into animal tissue. The name comes from the desired shape of the bullet after expansion.
Muzzle: The front end of a barrel. The point at which a projectile exits or 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 rapidly expanding gasses due to muzzle blast.
Muzzle Energy (ME): The energy of a bullet at the muzzle. At this point a bullet's energy is highest. See energy.
Muzzle Velocity (MV): The initial velocity of a projectile as it exits the muzzle. See velocity.
N
NBRSA: National Bench Rest Shooters Association Neck: The top portion of a case that grips the bullet. In a bottle necked case, it is the area immediately 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 Size: To resize part or all of the neck only, leaving the case body unchanged. Neck sizing is accomplished without the die touching the shoulder or body of a case. Neck Turn: An operation performed on the neck of a case to improve concentricity by reducing neck wall thickness from the outside by cutting to a uniform thickness, with a special tool. A great aid to accuracy.
NRA: National Rifle Association. O
OAL: Over All Length: The total length of a loaded cartridge. May also be listed as COL (Cartridge Overall Length).
P
Parallax: In rifle scopes, the condition exists when the reticle (crosshairs) does not lie exactly on the image plane. Excessive parallax makes the shooter's eye position off centered. Correct parallax is critical if repeatable accuracy is to be realized.
Personal Locator Beacon (PLB): Is a compact, portable emergency locating beacon, designed for individual use and carry. When activated by a lost or injured person, sends out distress signals to SAR (search and Rescue) Satellites on the 406 MHz frequency. The signals tell the ground crews where to find the distressed person, in rapid time.
Point Blank Range: (Also called Maximum Point Blank Range or MPBR) The maximum range at which a shooter can hit the vital zone of a target, without holding over or under.
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.
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 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.
Powder Measure: A reloading tool which dispenses a specific volume of powder. Most are set for a certain charge through the use of an adjustable powder chamber allowing the handloader to return quickly to that pre-set measure.
Powder Scale: A sensitive scale used to measure small powder charges, bullets, cases, etc. A good scale, accurate to within 1/10th of a grain, is an important tool for precise hand-loads. Balance Beam scales are normally used, but electronic scales have been gaining popularity for many years now. Powder Trickler: In reloading, mechanical accessory used to dribble powder, a kernel at a time, into the pan of a powder scale. Used when the handloader desires all charges to be absolutely uniform in weight.
Primer - The ignition component of a cartridge, made up of a small metal cup that contains a detonating mixture which is used to ignite the propellant powder. The primer is seated in the primer pocket in the base of the cartridge case.
Primer Pocket: The vented cavity in the base of a centerfire cartridge case made to receive and support the primer.
Primer Tool: A specialized tool which does only the priming operation. Normally used in referring to a hand-held priming tool. Propellant - In a firearm the chemical composition that is ignited by the primer to generate gas.
Progressive: A type of reloading press which advances a number of cases through the various stages of the reloading operation with every cycling. Once all stations are full, progressive presses turn out a loaded round with each stroke of the handle. 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.
Propellant: The technically correct term for ballistic chemicals, that make up powder, used to propel a projectile.
PSI: Pounds per Square Inch.
R
Range: 1. A place where shooting is conducted. 2. The horizontal distance of travel of a projectile from firearm to target. 3. Three terms apply to range: "point blank", "effective" and "maximum". Point blank refers to distances of five yards or less, effective range means the greatest distance a projectile will travel with accuracy, maximum range means the maximum distance a projectile will travel. Range-finder: an electronic device that sends a laser beam to a target, bounces off the target, and gives a read-out of the exact distance to the target in yards or meters.
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.
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.
Remaining Energy: The residual or "down-range" energy of a projectile, measured in foot pounds, at a given distance from the muzzle. Resizing: Returning a fired case to dimensions which will allow its being rechambered in a firearm. Normally accomplished via a resizing die, this may refer to full-length, neck, small-base, or partial resizing.
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.
Rifle - A shoulder fired firearm with rifling in the barrels bore, or rifled bore. rifle: (1) A modern firearm designed to be fired from the shoulder, generally having a barrel more than 15 inches long. Its main characteristic is a rifled (knurled grooved) barrel that imparts spin to a single projectile as it travels through the bore. Rifling: The series of spiral grooves, cut into the bore of a firearm, intended to induce spin and stability to a projectile in flight and impart accuracy. Rifling is present in all true rifles.
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 which establishes firearms standards in the United States.
Seating Depth: In a loaded cartridge, The depth to which the base of a given bullet is seated below the case mouth.
Sectional Density: A bullet's weight in pounds divided by the square of its diameter in inches. Shell Holder: The piece of a reloading press which holds the base of the case during the reloading process. Shell holders are different sizes, and removable, allowing one press to reload a wide variety of cases by changing to the appropriate size.
Shoulder: The sloping portion of a bottleneck cartridge case, located between the neck and the case 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.
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.
Slam Fire: A slam fire is the accidental discharge of the rifle during the feeding(of the bullet) cycle, with no action on the part of the shooter. The most common cause is handloaded ammunition with a high primer, improperly set head-space (insufficient resizing) or a combination of both. This is an extremely serious condition that can destroy the rifle and injure the shooter.
Stabilize: To spin a projectile around its long axis rapidly enough to keep it point-on in flight.
Survival Kit: A collection of foods, water, first-aid, and tools gathered before-hand, housed in a back-pack or small suit-case type bag that will help a person, or number of people survive or endure catastrophe for a pre-determined amount of time. Survival Skills: The ability to survive or endure adverse conditions or catastrophe through preparation beforehand of certain tools, techniques, and abilities, such as wilderness hardship camping, fire-making, shelter building, food and water storage, etc. And anticipating the usage of such items by developing talent through practicing and training.
T Target: (1.) made of paper, with grid-lines and a highly visible target-dot or "bullseye" used as an aiming reference and fired at with a firearm to determine the accuracy of projectiles. (2.) In the field the intended object you wish to accurately hit with a projectile.
Terminal Ballistics: The branch of ballistics which deals with the projectiles impact on target. Throat: That area of the bore immediately ahead of the chamber tapering to the point where the rifling starts.
Time of Flight (TOF): is the elapsed time, in seconds, of a bullet's flight from muzzle to a given point down-range. A critical factor to a number of ballistic program calculations.
Trajectory: The path of the projectile in flight relative to the line of sight. Refer to: Bullet Path.
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 revolution. A barrel that fully rotates a bullet every ten inches is said to have a “1 in 10” twist.
V Varmint: variation of the word "vermin." non-game animals, considered as pests, such as coyotes, crows, woodchucks, or prairie dogs. In most states, varmints are not protected with seasons or bag limits.
Varmint Rifle: A rifle built specifically for varmint shooting. Generally speaking, varmint rifles tend to be heavy-barreled, and chambered for small-bore, flat-shooting cartridges such as the 223, 22-250, or the 243 Win. Velocity: The speed at which a projectile travels, usually measured in feet per second or meters per second.
W
Wildcat: A non-standard cartridge or chambering. The distinction is, “wildcat” generally refers to a cartridge that has been altered from an existing commercial case to make a style that is not available from ammunition companies.
Windage: The amount of lateral correction (left ot right) of a firearms sights, to compensate for the projectiles natural deflection by wind-drift.
Wind Drift: Lateral change in the path of a projectile due to crosswind effects.
Work-hardening: The change in hardness and grain structure of brass due to repeated firings and reloadings. In reloading, continued sizing of a case can stress and flex the brass until brittleness, cracks and splitting occur. Usually in and around the neck area.
Working-up (a load) : 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.
Z Zero: (1.) To adjust sights of the firearm for a specific starting range by firing several trial shots at that range, with the absence of wind. (2.) The adjustment of a firearm's sights in order to obtain impact at a desired point in relation to a specific point of aim, at a given distance.
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