Action:

The part of a firearm by which it is loaded, fired and unloaded.

Anneal:

The process of altering the structure of metal so as to relieve it’s working stresses and increase it’s ductivity.

Antimony:

A metallic element which increases the hardness of lead when combined as an alloy.

Anvil:

A metallic part of the primer. The blow from the firing pin crushes the priming mixture against the anvil causing ignition.

Ball:

In military nomenclature this term refers to the bullet.

Ball Powder:

This is a trade name for a double-base smokeless powder developed by Olin Industries. The grains have a spherical, or flattened spherical shape.

Ballistics:

The science of projectiles in motion.

Ballistic Tip:

A unique rifle bullet designed by John Nosler that combines the qualities of the Nosler® Solid Base® (see SOLID BASE) bullet with a polycarbonate tip that resists deformation in the magazine or feed ramp of a rifle during recoil. These bullets have a higher ballistic coefficient than most other bullets of the equivalent size and weight due to the sharp, aerodynamic tip.

Ballistic Coefficient:

Ratio of the sectional density of a bullet to its coefficient form. Represents the projectiles ability to overcome air resistance in flight.

Barrel Cylinder Cap:

The gap or space between the cylinder and forcing cone of the barrel in a revolver.

Battery Cup:

A type of primer used in shotshells which makes use of an outside cup to support it in the case.

Bearing Surface:

That portion of the bullet surface which bears on, or touches, the bore.

Bell:

To open the mouth of a case slightly in order to seat a bullet more easily. Also used in reference to a rifle barrel which is worn at the muzzle (belled muzzle).

Belted Case:

A band which is formed into the head of some cases (magnum type) to strengthen the case and headspace of the cartridge.

Berdan Primer:

A common European priming system which makes use of an anvil formed in the case itself.

Boattail:

A bullet design having a tapered base.

Bore:

The inside diameter of a barrel before the rifling is cut.

Boxer Primer:

A type of primer used in all American rifle and pistol ammunition and featuring a self contained anvil. It is fitted in the primer pocket in the head of centerfire cartridge cases.

Brass:

A common term used by handloaders in referring to empty cartridge cases. An alloy of copper and zinc.

Bullet:

That portion of the cartridge which becomes a projectile when in flight.

Bullet Puller:

Tool used to remove bullet from case.

Burning Rate:

A term which is used to describe the rapidity with which a given powder will burn. The term itself is a relative one based on a comparison with other powders.

Calibre:

The approximate diameter of a bullet or bore, expressed in decimals of an inch in English. In Europe, where the metric system is used, this measurement is expressed in millimeter.

Cannelure:

A groove (or grooves) cut around the circumference of a bullet. These grooves, usually one to a bullet, provide the best means of securely crimping the case mouth into the bullet.

Case:

The metal, plastic or paper container which holds all of the components of a round of ammunition.

Case Neck Brush:

The metal or nylon brush and handle used to clean the inside of case necks.

Case Trimmer:

A device used to remove excess material from a case mouth. Metallic cases stretch after extensive reloading and firing because the brass flows forward. These cases must be trimmed back.

Case Trimmer Pilot:

The pilot guides the cutting portion of the case trimmer by fitting inside the neck of the case to be trimmed.

Cast Bullet:

Bullets for centerfire rifle or pistol which are cast from lead alloy. Muzzleloading projectiles and shotgun slugs are cast in pure lead.

Centerfire:

Refers to a cartridge having a centrally located primer in it’s base.

Chamber:

The part of the bore at the breech which is formed to accept and support the loaded cartridge.

Chamfer:

To ream a taper on the inside of a case mouth.

Charge:

The amount of powder used in the case at each loading. Also refers to the amount of shot used in a shotshell.

Choke:

A constriction at the muzzle of a shotgun barrel designed to control the spreading of shot.

Chronograph:

An instrument used to measure the velocity of a projectile.

Compressed Charge:

A charge of powder which so nearly fills the case that it is compressed when the bullet is seated.

Components:

Any of the various parts which go into the making of a cartridge.

Corrosion:

The eating away of the bore by rust or chemical action.

Crimp:

The bending inward of the case mouth to grip the bullet. With shotshells the term applies to the closure at the case mouth.

Crimped Primer:

A forcing inward of the brass around the top of the primer pocket. This is frequently found on military cartridges and is done to prevent set-back of primers. The crimp must be removed before repriming the case.

Cylindrical Powder:

Tubular shaped smokeless powder which is manufactured by an extrusion process.

Deburring Tool:

The deburring tool removes burs from the inside and outside of any newly trimmed case mouths

Decap:

To deprime a case by removing the spent primer from the primer pocket, most often accomplished by the decapping pin in a die during the resizing operation of reloading.

Die:

A tool, in handloading, that reforms cartridge cases and seats bullets; or, in bullet manufacture, a tool that swages bullets or cores, extrudes lead wire or draws jackets.

Double Base Powder:

Dram Equivalent:

Term used to indicate the approximate velocity of a shot charge by comparison.

Drift:

Deviation of a projectile from the line of departure due to its rotational spin or the force of wind.

Drop:

The distance a projectile falls, calculated from the line of departure.

Double Base Powder:

Smokeless powder made with nitroglycerine and nitrocellulose base.

Drift:

A term used in exterior ballistics to describe the deviation of a projectile laterally from the line of departure. Typically caused by wind.

Drop:

The effect of gravity on the projectile. The distance between the line of departure and the trajectory at a given distance.

Duplex Load:

The use of two different powders in loading the same cartridge.

Energy:

A projectile’s capacity for doing work at a given range, expressed in foot-pounds.

Erosion:

The wearing away of the bore due to friction and/or gas cutting.

Expander Ball (Button):

A thicker section of the decapping stem, used to expand the case mouth to the precise diameter required to hold the bullet firmly.

Extruded Powder:

An indication of excessive pressure shown by a ring or “cratering” around the primer indent where the primer has been extruded into the firing pin recess on the bolt face.

Fireform:

Reforming or changing the shape of a cartridge case by firing it in a chamber of a desired shape.

Flash Hole:

A hole leading from the primer pocket to the inside of a case.

Flake Powder:

Thin, round, flake-type of smokeless powder which is usually of a fast-burning nature.

Foot-Pound:

A unit of kinetic energy equal to the effort required to raise one pound of weight; to put a height of one foot, against the normal pull of gravity.

FPS (Feet Per Second):

The measurement used to describe the velocity of the projectile.

Freebore:

The distance in the barrel, if any, which the bullet travels before it contacts the rifling. Some barrels are purposely relieved to allow the bullet considerable free movement before it strikes the rifling.

Gas Checks:

A gliding metal cup which is used to protect the base of a cast lead alloy bullet from the effects of burning powder gases.

Gliding Metal:

A copper-zinc alloy used for bullet jackets and gas checks.

Grain:

A unit of weight measure. 437.5 grains equal one ounce; 7000 grains equal one pound.

Grooves:

The spiral cut that is removed from the bore to leave the “lands.” The grooves of a .30 caliber rifle are approximately .308” in diameter.

Hangfire:

Delayed ignition.

Headspace:

The distance from the breech face to the part of the chamber which acts as a stop and prevents the cartridge from moving forward. Also applies to the cartridge case.

Heel:

The outer edge of the bullet base.

Hollow Point:

A bullet design which features an axial hole at the point. The purpose of the hole is to aid expansion on impact.

Hydrostatic Shock:

A highly destructive shock wave created by a bullet passing through animal tissue, which is high in water content.

Ignition:

The action of setting the powder charge on fire.

IMR:

Abbreviation for “Improved Military Rifle”.

Jacket:

The covering or “skin” of a bullet.

Keyhole:

The imprint of a bullet which struck sideways on target rather than point first.

Lands:

The raised portion of the rifling.

Line of Sight:

An imaginary straight line from the eye, through the sights, to the point of aim.

Loading Density:

Ratio of the volume of the powder charge to the volume of the case. The higher the better in terms of accuracy.

Lube Dent:

A dent in the cartridge case caused by using too much lubricant when resizing.

Lube Pad:

A pad, impregnated with lubricant, on which cases are rolled before resizing.

Lubricant:

Case sizing lubricant reduces friction between the case and die during the resizing operation in reloading.

Mecuric Primer:

A primer in which the priming material contains mercury.

Meplat:

The meplat (from the French word "méplat" meaning "flat surface of a cylinder") is the technical term for the flat or open tip on the nose of a bullet. The shape of the meplat is important in determining how the bullet moves through the air. In particular the size and shape of the meplat has a significant effect on the ballistic coefficient of a bullet.

Metal Case (MC):

A type of bullet, except for a small opening at the base, is completely encased in a jacket.

Mid-Range Trajectory:

Refers to the distance the bullet rises above the line of sight. Mid-range trajectory is calculated halfway between the muzzle and the target.

Minute-of-Angle:

A unit of angular deviation equal to 1/60th of a degree. For practical purposes, it is usually approximated as equal to one inch at 100 yards.

Misfire:

The failure of a cartridge to fire after the primer was struck.

Muzzle:

The front end of the barrel.

Muzzle Energy:

See “Energy”

Neck:

The upper portion of a cartridge case that grips the bullet.

Neck-Size:

To resize only the neck portion of a case.

Non-Corrosive:

Usually refers to primers having a priming mixture which is free of corrosive compounds. Modern primers are non-corrosive.

Obturation:

Obturation in firearms is the result of a bullet expanding or upsetting to fit the bore, or, in the case of a firearm, of a brass case expanding to seal against the chamber at the moment of firing. In the first case, this both seals the bullet in the bore, and causes the bullet to engage the barrel's rifling. In the second case, it seals the case in the chamber and prevents backward travel of gases against the bolt. The thin brass case easily seals the chamber, even in low pressure rounds.

Ogive:

Refers to the nose shape of the bullet. The radius of the curve of a bullet nose.

Powder:

The propellant used in most firearms. It produces a large volume of gas when ignited. There are two basic types; smokeless and black powder.

Powder Funnel:

A helpful accessory that facilitates transfer of powder from a scale pan or measure to a cartridge case.

Powder Measure:

An adjustable volumetric measure that meters out uniform charges of powder.

Powder Scale:

A device to weigh charges of powder. A beam scale is a scale where markers, called “poise”, are moved along a weight graduated beam, as the pan is filled with powder, until the balance point is reached. An electronic device used to measure the weight of powder in grains or grams.

Pressure:

The force exerted by a burning charge of a powder in the chamber of a firearm. Expressed normally in pounds per square inch.

Primer:

A small metal cap containing the detonating mixture which is used to ignite the propellant charge.

Primer Pocket:

The cavity in the base of a cartridge which receive and supports the primer.

Ram:

The main shaft of a metallic cartridge reloading tool.

Resizing Die:

The reloading die that resizes fired cartridge cases and removes spent primers by means of a decapping pin.

Round:

A military term meaning one single cartridge.

Round Nose (RN):

A bullet design which features a rounded nose.

SAMMI:

An abbreviation for “Sporting Arms and Ammunition Manufacturers Institute”.

Seating Depth:

The depth to which a bullet is seated below the case mouth.

Seating Die:

The reloading die that presses the bullet into the neck of the cartridge case, crimping the case if so desired.

Seacant Ogive:

A secant ogive is an ogive that tapers more gradually relative to its length than does the tangent ogive and touches the curve at two places, which provides a higher Ballistic Coefficient (BC) and less drag.

Sectional Density:

A bullets weight, in pounds, divided by the square of it’s diameter in inches.

Shell Holder:

This is attached to the top of the ram and holds the heads of the cartridge cases as they are moved up and down, into and out of the die.

Swage:

To pressure-form by forcing through or into a die.

Throat:

That area of the bore immediately ahead of the chamber.

Trajectory:

The path of a projectile in flight.

Trim-to-Length:

The length a cartridge case should be trimmed to after it has stretched past its maximum case length.

Turret Press:

A reloading press with a rotatable multi-station turret top for positioning dies and powder measures in their appropriate sequence.

V-Bull:

Centre of a target - Bull's Eye.

Velocity:

The speed at which a projectile travels. It is usually measured in feet per second at a given range.

Vernier Caliper:

A slide-type graduated instrument is used to measure overall cartridge and case lengths precisely.

Wad Cutter (WC):

A bullet design which features a sharp shoulder. Designed to cut a clean round hole in a paper target.

Web:

That portion of a cartridge case between the bottom of the primer pocket and the interior of the case.

Work-Harden:

Brass becomes harder as it is worked. See “Anneal”.

X-Ring:

Centre of a target. Bulls-eye.

Yaw:

The action of a projectile spinning erratically around it’s own axis.

Zero:

The ranges at which a firearm will hit the point of aim.