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ACP: Abbreviation for Automatic Colt Pistol. Normally used to designate a cartridge, as in the 45 ACP.

Ammunition: An assembled group of components, bullet, primer, cartridge case and powder, necessary for loading and discharging a firearm. Frequently abbreviated as “ammo”.

Anneal: A heat treating process which can be used to restore the ductility to brass that has been work hardened. In the case of brass, annealing always softens the metal.

Antimony: A metal, frequently used to harden lead by alloying the two. Other metals, such as tin, may be added to the alloy as well.

Anvil: A point against which priming compound can be crushed by the blow of the firing pin, causing detonation. Anvils may be a separate piece pressed into the primer itself (Boxer type), or an integral part of the case, as in the Berdan system.

Automatic Weapon: Any firearm which discharges multiple shots with a single actuation of the trigger. In common usage, the term is often applied erroneously to describe what should be described as an autoloading, semi-automatic or self-loading firearm.

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Backed-Out Primer: A primer which, upon firing, has been pushed slightly out from the primer pocket. Primers backing out generally indicates an excessive headspace situation, usually in conjunction with a light load. Can be caused by light loads alone, in some circumstances. Also referred to as a popped or protruded primer.

Ballistics: The science of projectiles in motion. When applied to firearms, it is normally divided into interior ballistics, exterior ballistics, and terminal ballistics.

Ballistic Coefficient: A mathematical expression of a bullets ability to overcome atmospheric resistance (drag), as compared to a specified “standard” reference projectile. Generally abbreviated as BC.

Balloon Head: A drawn cartridge case in which the primer actually extends into the powder chamber. This results in a rather weak web area, making the cases suitable for light loads only. Although long discontinued, they may still be encountered in old cartridges such as the .45 Colt, .44-40 WCF, or .45-70 Government. Balloon head cases are best relegated to the case collector, and should not be reloaded.

Ball: Military nomenclature for a single round of small-arms ammunition. Refers specifically to lead or steel-cored jacketed ammunition, as opposed to more specialized tracer or armor-piercing ammunition.

Ball Powder: Any of a series of double-base powders developed by Olin, having a spherical or flattened spherical shape. Examples would include Winchester’s 231, 748, or 760 powders.

Barrel/Cylinder Gap: The distance from the face of a revolver’s cylinder to the face of the barrel. Normally, this is somewhere in the range of .003" TO .006", depending on the manufacturers specifications.

Battery: As applied to firearms, the position of readiness for firing. A firearm is referred to as being “in-battery” when the locking mechanism is fully closed and the action is ready to be fired.

Bearing Surface: The area of a bullet which actually contacts the lands and grooves during its passage through the barrel.

Belted Case: A case having a raised band, or belt, around the base just ahead of the extractor grove. Intended to provide positive headspacing on cartridges with long, sloping shoulders, the belt allows the cartridge to feed and function more reliably than a rimmed case. Contrary to the common misconception, the belt adds nothing to the strength of the case.

Berdan Case/Primer: A primer/case system, designed by Col. Hiram Berdan, having two or more flash holes, and an anvil formed into the primer pocket. Although widely used throughout the world, this system has never been popular in the U.S., due largely to the difficulty in reloading Berdan cases.

Black Powder: An explosive propellant composed of potassium nitrate, charcoal, and sulfur.

Blitz: Sierra’s line of thin-jacketed bullets, designed to expand or fragment violently upon impact. Especially favored for varmint hunting where ricochets may be a problem.

BlitzKing: Any of Sierra’s family of high-performance varmint bullets utilizing an acetal resin tip. Combining high ballistic coefficient and outstanding accuracy with explosive terminal performance, they offer varminters the ultimate in field effectiveness.

Boat Tail: A tapered section between a bullets bearing surface and base, intended to reduce the effects of drag. This, in turn, gives the bullet a higher ballistic coefficient than a comparable flat-based bullet.

Bolt: That portion of a firearms action which contains the extractor and firing pin/striker mechanisms. It may or may not also serve to lock the mechanism.

Bolt Thrust: The force exerted on the bolt face by gas pressure upon ignition, normally expressed in units of pounds per square inch (psi).

Bore: The inside portion of a barrel. In a rifled barrel, the bore diameter refers to the measurement from the top of one land, to the top of the opposing land; the inside diameter of the barrel before the rifling is cut.

Bore Capacity: A term used to describe the volume of the bore as it relates to its ability to effectively burn a given amount or type of powder, with a certain combination of components. A cartridge which may be “over bore capacity” with one type of powder, may be perfectly suited to another powder of a different burning rate. Specifically, bore capacity for a given component combination is indicated by the point (or DELTA) at which the pressure and velocity curves begin to separate.

Bore Guide: An aid used during the cleaning process to help keep the cleaning rod centered in the bore, reducing the chance of damage to the throat. May replace the bolt, in the case of bolt action rifles, or may fit over the muzzle, as with the M14. Sometimes called a “cleaning bolt.”

Bore Sight: To bring the sights into rough alignment with the bore visually, or with a collimator. Bore sighting is done in preparation to firing for zero; it is never a replacement for actual firing.

Boxer Case/Primer: A primer/case system, designed by Col. Edward Boxer, having one flash hole located in the center of the primer pocket and a separate anvil pressed into the primer cup. Due to its ease of reloading, the Boxer system is best suited to the handloaders needs. Ironically, the system invented by an Englishman (Boxer) is most prevalent in the U.S., while an American system (Berdan’s) is used in England and Europe.

Brass: An alloy of copper and zinc. Brass is the most commonly used material from which metallic cartridge cases are made. The term is also frequently used to describe the cartridge cases themselves.

Bridging: A “logjam” type accumulation of powder in the mouth area of a powder measure, which sometimes occurs when using extruded tubular powders. This causes one charge to be light, and the next charge thrown to be excessive when the bridged powder falls free; a potentially hazardous situation.

Brisance: The shattering or crushing effect of an explosive.

Bullet: The projectile fired from a firearm. A complete, loaded cartridge is not a bullet; although a bullet is part of a loaded cartridge.

Bullet Path: The vertical distance, normally expressed in inches, above or below a firearms line of sight. The path followed by a bullet in its flight to a target.

Bullet Pull: The amount of pull, normally measured in pounds, needed to pull a bullet from the case mouth. Also referred to as “neck tension”.

Bullet Puller: A tool used to extract a bullet from a case or loaded cartridge or loaded ammunition, or to break down ammunition which would be unsafe to fire.

Burning Rate: A term used to describe the relative quickness of a given powder as compared to a known standard. Burning rate is extremely important in determining a powders suitability for a given cartridge.

Bushing Die: A sizing die, either 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.

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Caliber: The diameter of a projectile, normally expressed in thousandths of an inch when discussing small arms, although it may also be expressed in metric units. May also refer to bore or groove diameter, again, either in inches or millimeters.

Caliper: A measuring instrument consisting of adjustable jaws used to determine thickness, diameter or length. An essential tool for the handloader.

Cannelure: A cut or pressed groove (or grooves) around the shank of a bullet. Cannelures provide an area into which the case mouth may be securely crimped. Also known as “crimping grooves.”

Cap: A percussion cap. The percussion cap was a early form of primer, composed of a small metal cup charged with a priming mixture (such as fulminate of mercury). Percussion caps are still used in most black powder firearms. Although not technically correct, the term is still used in reference to primers.

Cartridge: A single, complete round of ammunition. See “ammunition”. The first cartridges consisted of the components (powder and bullet) which were contained in a casing of paper. The term “cartridge” comes from the Latin word for paper, “charta”, a direct reference to these early beginnings. Modern cartridges normally consist of 1) a case, 2) a bullet(s), 3) a primer, and 4) the powder charge.

Case: The portion of a cartridge which holds or contains all other components. Also known as a “shell”, “brass”, “cartridge case” or “hull”.

Case Forming: Forming a case, such as a .30-06, into another, such as a .25-06. This may be accomplished by the use of dies alone, or it may involve fire forming. Also referred to as “reforming.”

Case Trimmer: A tool for cutting cases back to length after being stretched by firing or reforming.

Cast Bullet: A bullet produced by pouring molten lead (or lead alloy) into a mould.

Center Fire: Ammunition which has a primer located in the center of its base. Most center fire cartridges are reloadable.

Chamber: That area of a firearm into which the cartridge is loaded in preparation for firing, and which supports the cartridge during firing.

Chamber Cast: A casting of a firearms chamber(s), normally done with Woods metal, Cerrosafe, or a similar low melting-point alloy. Making a chamber cast is sometimes necessary to check chamber or throat dimensions.

Chamfer: To remove burrs on the inside of a case mouth by cutting a slight bevel or taper. Chamfering reduces the possibility of damage to the bullet base, or the case itself, during the seating process.

Charge: The specified amount of a particular powder loaded into a case. The act of putting powder into a case.

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. Chronographs, while long used by the military and commercial ammunition manufacturers, have only become commonly available to the handloader within the last 20-30 years.

Clip: A device which holds ammunition to be charged into a magazine. Clips may be inserted into the firearm and remain there during firing, as with the M1 Garand, or may be used only to aid in charging the magazine, as with the 1903 Springfield, M14, or M16s. This latter type is referred to as a “stripper clip”, while the former is called a “charger clip.”

CMP: The Civilian Marksmanship Program. The CMP was originally created by the U.S. Congress. The CMP evolved out of the older (and no longer operational) Director of Civilian Marksmanship. The original purpose was to provide civilians an opportunity to learn and practice marksmanship skills so they would be skilled marksmen (or marksmanship instructors) if later called on to serve the U.S. military. The CMP operates through a network of affiliated clubs and associations that cover every state in the U.S.

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 is never a replacement for range firing.

Compressed Charge: A load in which the seating of the bullet actually causes some compression of the powder. This situation is quite normal when using some of the slower-burning powders commonly used in the large-capacity Magnums.

Cordite: An early extruded, smokeless, double-base propellant widely used in England. Cordite is distinguished by its length, which normally ran the full length of the powder chamber. Invented in 1889, cordite served as the basis for many of our currently used extruded propellants.

Corrosive Primer: Any primer using potassium chlorate in its priming compound. When fired, a portion of this will become potassium chloride, similar to common table salt, and be deposited in the barrel, causing corrosion (rusting) very rapidly. Cleaning, using normal powder and copper solvents will not remove the corrosion causing residue left in the bore. These deposits can easily be removed by using warm water, followed by standard cleaning and oiling.

Crimp: A turning inward of a case mouth to increase its tension on a bullet. Crimping is necessary when loading for revolvers, tubular magazines, and some rifles with extremely heavy recoil.

Crimped Primer: Refers to a primer which has been staked, stabbed or otherwise crimped into the primer pocket. Commonly found on military cases, the remnants of this crimp must be removed by swaging or reaming before another primer is seated.

Crown: The point of the bore where the rifling terminates at the muzzle.

CUP: Abbreviation for “Copper Units of Pressure”. This relates to the pressure measured in a copper crusher testing system. There is no direct correlation between CUP and pressure expressed in pounds per square inch (PSI), and no conversion factor to extrapolate one from the other.

Cupronickel: An alloy of copper and nickel, also known as “German Silver.” Cupronickel was once used extensively as a jacket material, despite a serious tendency to leave metal fouling in the barrel. In the U.S., it has been replaced almost entirely by gilding metal.

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DCM: Director of Civilian Marksmanship

Deburr: To remove any burrs around the inside or outside of a case mouth. Burrs are a normal byproduct of case trimming, and must be removed before reloading the case.

Decap: To remove a spent primer from a case.

Deterrent Coating: A chemical coating applied to powders, in order to bring their burning rates and characteristics into line with the manufacturers specifications for that particular powder type.

Dies: In reloading, the tooling by which the resizing, reforming, case neck expanding, bullet seating, or bullet swaging operations are performed. Normally used in conjunction with a reloading press.

Double-Base: A powder which uses both nitrocellulose and nitroglycerine as an explosive base, as opposed to a single-base powder, which uses only nitrocellu-lose. Double-base powders generally have a higher energy content, and as such, can be somewhat more erosive than comparable single-base powders.

Drop: The vertical distance between the bullet and its line of departure, normally measured in inches at a given range. Drop is caused by the effects of gravity upon a projectile.

Drop Tube: A powder funnel having a short length of tubing (usually 5" to 6") to settle the powder kernels more compactly within the case. The result is an increase in the amount of propellant which can be charged into the case.

Dum-Dum: A term applied to some early expanding bullets for the .303 service cartridge loaded by the British arsenal at Dum-Dum, India, prior to 1899. Frequently used (incorrectly) by the media and others unfamiliar with firearms to indicate any expanding bullet.

Duplex Load: A load utilizing two different type of powder; usually a faster powder near the primer, and a slower one for the main charge. Duplex loading is intended to give higher velocities, smoother pressure curves, and greater powder efficiency.

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Energy: The capacity for performing work. 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.

Engraving: The impressed indentations left on a bullets bearing surface, during its passage through the bore.

Erosion: The wear, usually in the throat area of a barrel, caused by extreme heat and friction. Erosion occurs in all firearms but is aggravated by rapid fire, large case capacity, or the use of hotter burning powders.

Expander Ball: A ball or plug, used to expand a case mouth to accept a bullet. In dies for bottlenecked cases, the expander is usually found on the decapping stem. An expander ball should be approximately .001" to .002" under bullet diameter to assure proper neck tension.

Expansion Ratio: A mathematical expression for the relationship of the volume of the bore and powder chamber, to that of the powder chamber alone. Expansion ratio is a critical factor in predicting the performance capabilities of a gun/cartridge combination.

Exterior Ballistics: The branch of ballistics which deals with the projectiles flight, from the time it leaves the muzzle, until it impacts on target.

Extruded Tubular Powder: A type of smokeless powder formed by forcing it through a die, and cutting it to specified length. Extruded tubular powders are more or less cylindrical in shape, and may have one or more perforations running through its length. Common examples of extruded powders are IMR 4350, H4895, or Accurate 3100.

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Far Zero: The second point at which the bullet path crosses the line of sight. This is the commonly referred to “zero” for a given firearm, at which the point of aim and point of impact coincide.

Fireform: To alter the shape of a case by firing it, generally done to increase case capacity. Upon firing, pressure forces the case out to fit the chamber, creating the new dimensions desired. Fireforming is a common technique in making wildcat or improved cases.

Firing Pin: That portion of a firearm which strikes the primer, causing ignition.

Flash Hole: A hole, or holes, from the primer pocket to the powder chamber of a cartridge case.

Flat Nose: A bullet design having a broad, flat, meplat. In most tubular magazines, the point of one round rests on the primer of the cartridge in front of it, creating a potentially hazardous situation. Flat nose bullets are intended for use in these magazines to reduce the possibility of recoil causing detonation in the remaining rounds.

FMJ: Common abbreviation for “Full Metal Jacket”, indicating a bullet having no exposed lead on the frontal portion. FMJ’s are non-expanding bullets, used in both rifles and pistols. They are produced in several different configurations, i.e., round nose, spitzer, spitzer boat tail, etc., depending on their intended use.

Forcing Cone: The section of a revolver or shotgun barrel just ahead of the chamber(s) which gradually reduces in diameter to bore or land diameter. The forcing cone serves to align the bullet or shot charge with the bore, while preventing deformation to the projectile(s).

FPJ: Full Profile Jacket. Sierra’s designation for a line of pistol or revolver bullets which have the jacket extending to the nose of the bullet. FPJs are intended to hold together well on silhouettes and other targets requiring deep penetration and minimal expansion.

FPS: Abbreviation for “Feet Per Second”, usually in reference to the speed of a given projectile(s).

Freebore: Essentially, the throat area of a barrel. Normally, use of the term “free-bore” indicates the rifle in question has an unusually long throat, as is the case in most of the Weatherby chamberings.

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GameKing: Sierra’s line of boat tailed hunting bullets. GameKings may be either hollow-point or spitzer in configuration, but all are of boat tail design.

Gas: The rapidly expanding vapor caused by combustion. As the gas expands in an enclosed chamber (the cartridge case), it generates tremendous pressure. It is this pressure which drives the projectile to the target.

Gas Check: A protective cup of copper, brass, or gilding metal placed on the base of a cast bullet. Gas checks are intended to reduce deformation of the bullets base due to pressure or hot gases.

Gas Operated: In firearms, a gun system which utilizes a portion of the gases produced by the powders combustion to cycle the action. The military M1, M14, and M16 are all examples of gas operated weapons.

Gilding Metal: An alloy of 90 to 95% copper, 5 to 10% zinc, now used extensively as a jacket material.

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.

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. While there are several ways of measuring group size, the most common for the average shooter is the extreme spread of the two widest shots.

Gun Powder: The propellant powder used in cap and ball, muzzle- loading, and black powder cartridge firearms. Although frequently applied to any small arms propellant, the term “gun powder” denotes black powder specifically.

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Hangfire: A delay, sometimes quite noticeable, between the strike of the firing pin and the actual ignition of the 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. Insufficient headspace will cause difficulty in chambering, while excessive headspace will result in head separations. Headspace problems may be the fault of either the gun, the 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.

Heel: The slight radiused portion of a bullet between the base and the main body.

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 any form of autoloading firearm.

Hollow Point: A type of bullet having an opening in the nose. Hollow points may be of either the hunting, or target styles. Contrary to popular opinion, hollow points are not always designed to expand on impact. Match grade hollow point target bullets, for example, rarely exhibit any expansion when used on game.

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Ignition Time: The time interval between the impact of the striker or firing pin on the primer, and a rise in pressure sufficient to start the bullet from its seat.

IHMSA: International Handgun Metallic Silhouette Association

Improved: A cartridge having increased capacity over another “parent” case. Usually achieved by increasing the shoulder angle, decreasing the body taper, or both. This is most frequently accomplished by fireforming.

IMR: Improved Military Rifle. A series of single-base extruded tubular powders developed by Du Pont. Currently being manufactured by the IMR powder company.

Ingalls’Tables: A set of ballistics tables computed by Col. James Ingalls, in which the drag characteristics of a “standard” projectile are used as a reference for comparison of other small arms bullets. The ballistic coefficients of almost all U.S. manufactured bullets can be referenced to Ingalls’ tables, with only a slight degree of error.

Interior Ballistics: The branch of ballistics dealing with events occurring between the detonation of the primer and the projectile leaving the muzzle.

Instrumental Velocity: The velocity of a projectile as registered on a chronograph. Instrumental velocity is the average velocity of the projectile as it traverses the distance between the “start” and “stop” screens of the unit; in short, the velocity midway between them. If an actual muzzle velocity is needed, the instrumental velocity must be corrected to the muzzle. With modern chronographs, given their short screen spacings and a “start” screen only a few feet in front of the muzzle, this is generally unnecessary, and the corrections rarely amount to more than a few feet per second.

IPSC: International Practical Shooters Confederation

IWBA: International Wound Ballistics Association

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Jacket: An 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 standard for the industry.

JHC: Jacketed Hollow Cavity. A line of expanding handgun bullets designed by Sierra. JHCs are distinguished by having an internal cavity larger than the opening at the meplat.

JHP: Jacketed Hollow Point. Any of Sierra’s line of hollow point pistol bullets, primarily intended for use in autoloading handguns. Jacketed hollow points are designed to provide reliable feeding, while maintaining excellent expansion characteristics.

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Kernel: A single, individual piece of powder. Sometimes also referred to as a grain of powder, but must not be confused with the unit of weight. See “Grain”.

Key Hole: A elongated hole on target, indicating that the bullet was not traveling point-on at impact. Keyholing may be a slightly “out-of-round” hole, or it may be a complete bullet-shaped hole, where the projectile actually went through the target sideways. This normally indicates a stability problem.

Kinetic Energy: See “Energy.”

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Land(s): The raised portions of bore extending above the grooves in a rifled barrel.

Leade: The minute portion of a barrels rifling which slopes from the unrifled throat to the full-depth rifling. Although frequently referred to as the throat, there is a definite difference between the two.

Leading: A build-up or accumulation of lead in the barrel of a firearm, caused by using cast or swaged bullets. This can be controlled to a considerable degree by using harder alloys, better lubricants, or lower velocities. Leading causes no permanent harm to a firearm, but is detrimental to accuracy and can be difficult to remove.

Line of Departure: A straight line projecting through the axis of the bore to infinity. While this is the initial direction of a bullet’s velocity, it should be clearly understood that the bullet falls away from this line immediately upon leaving the muzzle. This is primarily due to gravity and other outside forces acting on the projectile.

Line of Sight: A straight line passing through the sights of a firearm to the target.

Load Density: The weight of the powder charge in grains, divided by the volume (frequently expressed in grains of water) 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, although there are exceptions.

Lock Time: The time interval between the sear’s release of the striker or firing pin, and the subsequent impact on the primer.

Lubricant: Any substance used to reduce friction. Specific types are used for firearm mechanisms, cast bullets, or case resizing.

LUP: Abbreviation for “Lead Units of Pressure”. This relates to the pressure measured in a lead crusher testing system. Most often used in low-pressure applications such as shotguns. There is no direct correlation between LUPs and pressure expressed in pounds per square inch (PSI), and no conversion factor to extrapolate one from the other.

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Machine Gun: An automatic weapon firing a full-size (rifle caliber or larger) cartridge, usually fired off a bipod, tripod or other fixed mount. They may be clip, magazine or belt-fed, depending on the design and intended use. They are most often employed as a crew-served weapon.

Magazine: An ammunition reservoir from which cartridges are fed into a firearms chamber. Magazines may be integral, as in the 1903 Springfield, or may be detachable, as in M14 and M16 series of weapons. Although the terms are frequently used interchangeably, a clip and a magazine are not the same thing.

Magnum: A designation sometimes attached to a cartridge of greater capacity or power than others of similar caliber. This can be misleading, as magnum cartridges are not always the most powerful in their respective bore sizes. In rifles, the term usually refers to one of the belted cartridges, based on the original Holland & Holland magnums. Today, belts are used more for sales appeal than any true ballistic function.

MatchKing: The trade name given to any of Sierra’s match-grade target bullets. All currently produced MatchKings are of hollow-point design, with all but one (.224" diameter 53 grain MatchKing) having boat tails. Despite their hollow-point design, MatchKings are not intended to expand on impact, and should not be used for big-game hunting.

Meplat: The diameter of the flattened tip at the nose of a bullet.

Mercuric Primer: Any primer which uses fulminate of mercury as a component in its priming compound. Cases fired with mercuric primers should not be reloaded, as the mercury seriously weakens the brass when fired. Mercuric primers may be either corrosive or non-corrosive, depending on whether or not they contain potassium chlorate. While no longer in use, surplus military and old commercial ammunition may still be encountered which is loaded with these primers.

Metal Fouling: Metallic residue left in a barrel after firing. Although the current use of gilding metal has reduced fouling problems, the shooter still needs to keep a close eye on the condition of the barrel. This fouling, normally seen as a copper wash in the bore will have a detrimental effect on accuracy.

Minute Of Angle: A unit of angular measurement equaling 1/60th of a degree. One minute of angle works out very close to one inch per hundred yards, making it a convenient measurement for shooters to use in describing accuracy, sight elevation or windage deflection. Also referred to as “MOA,” or “minutes.” One minute of angle = 1.0472" @ 100 yards.

Misfire: The complete failure of a cartridge to fire after being struck by the firing pin or striker.

Momentum: Expressed in units of “pound-seconds,” momentum is a quantity of motion. Momentum is obtained by multiplying a bullets mass times its velocity. In many instances, momentum may be a better indicator of a bullet’s potential than kinetic energy.

Muzzle: The end portion of a firearms barrel; the point from which the bullet exits.

Muzzle Energy: The kinetic energy generated by a projectile as it leaves the muzzle.

Muzzle Pressure: The gas pressure remaining as the bullet exits the muzzle. High muzzle pressures tend to produce greater muzzle blast.

Muzzle Velocity: The initial velocity of a projectile as it exits the muzzle.

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NBRSA: National Bench Rest Shooters Association

Neck: The parallel-sided portion of a case that grips the bullet. In a bottlenecked case, it is the area immediately ahead of the shoulder.

Neck Up or Down: To change the size of a case neck, to reload with a bullet of larger or smaller diameter than the parent cartridge. As an example, the .30-06 case could be necked up to form a .35 Whelen, or necked down to form a .25-06. This is normally accomplished either by a sizing die, or by fireforming.

Neck Size: To resize only the neck area of a cartridge case. Neck sizing is accomplished without the die touching the shoulder or body of a case.

Neck Turning: An operation performed on the neck of a case to improve concentricity. This is accomplished by cutting the outside surface of the necks to a uniform thickness, while the case is centered on a mandrel.

NM: National Match. A reference or marking commonly used on firearm parts or ammunition to denote a more stringent level of manufacture or quality control. Most frequently associated with Service Rifles used in High Power competition, and Service Pistols used for the Conventional Bullseye National Match Course.

Non-Corrosive Primer: A primer which contains no potassium chlorate or similar compounds in its primer mixture. Also refer to: Corrosive Primer, and Mercuric Primer.

Non-Mercuric Primer: A primer which contains no fulminate of mercury, or other mercuric compound in its priming mixture. A mercuric primer may or may not be corrosive, depending on whether or not it contains potassium chlorate. Also refer to: Mercuric Primer, and Corrosive Primer.

NRA: National Rifle Association

NRMA: National Reloading Manufacturers Association

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OAL: Over All Length: The total length of a loaded cartridge. May also be listed as LOA (Length Over All), or COL (Cartridge Overall Length).

Obturation: The sealing of a bore and chamber by pressure. During the firing process, pressure swells the case within the chamber, preventing gas from leaking back into the action. The same pressure, applied to the base of the projectile causes it to swell or upset, filling and sealing the bore.

Ogive: Literally, a French word meaning “pointed arch.” In bullet design, the ogive is the radiused portion between the bearing surface and the meplat. This radius is often measured in “calibers.”

OKH: A series of cartridges designed by Charlie O’Neil, Elmer Keith, and Don Hopkins.

Out of Battery Firing: A discharge that takes place when the firearms locking mechanism is not fully closed. Unlike a slam-fire, an out of battery firing is normally the result of the shooter intentionally pulling the trigger. Upon firing, the unsupported case may rupture and vent gasses back into the action. This is a very hazardous situation for the shooter, and can destroy the rifle.

Overbore: A loose term used to describe a case that has more capacity than it can effectively use with normally available powders. Also see: Bore Capacity, and Expansion Ratio.

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Pierced Primers: A primer which, upon firing, has been pierced by the firing pin. This allows gas to flow back into the action, and can damage the bolt face. A potentially dangerous situation normally indicating excessively high pressures.

Plinking: Informal shooting, not following any organized rules of competition. Plinking is shooting “just for fun,” but all the rules of safe gun-handling still apply.

Point Blank Range: The range to which a shooter can obtain a hit in the vital zone of a target, without holding over or under. Point blank range is influenced by many variables, including target size, initial velocity, and ballistic coefficient. This term is frequently misused to refer to extremely close ranges. In reality, a target may be within point blank range even when it is several hundred yards away, depending on the variables mentioned.

Port Pressure: Applies only to gas operated firearms. The amount of pressure remaining in the bore as the bullet passes the gas port. If port pressures are too high, damage can result from the violent cycling of the action. It is important to understand that this can occur, even when chamber pressures are within acceptable limits. Port pressure can be controlled by proper powder selection.

Powder Measure: A reloading tool which dispenses a specific volume of powder. Most are set for a certain charge through the use of bushings, or an adjustable powder chamber. Several of the better units have micrometer adjustable thimbles, allowing the handloader to return quickly to pre-recorded settings.

Powder Scale: A scale used to measure powder charges, bullets, cases, etc. A good scale, accurate to within 1/10th of a grain, is an important tool for the hand-loader. Most reloading scales have traditionally been of the balance-beam type, although electronic units are now becoming quite popular.

Powder Trickler: A reloading tool used to dribble powder, a kernel at a time, into the pan of a powder scale. Normally used when the handloader desires all charges to be absolutely uniform in weight.

Power Jacket: A Sierra design feature, incorporated into both rifle and handgun bullets. A series of “skives” are cut into the mouth of a jacket, to promote uniform and positive expansion.

Pro-Hunter: Any of Sierra’s flat-base hunting bullets. Depending on their intended use and caliber, Pro-Hunters are available in a wide range of weights and nose configurations.

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.

Proof Cartridge: A special high-pressure load used to test the strength of a newly manufactured or rebuilt firearm. Also referred to as a “blue pill” load, pressures in these rounds may run as much as 40% higher than standard for a given cartridge.

Protruding Primer: Refer to: Backed Out Primer.

PSI: Pounds per Square Inch.

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Reforming: To alter the dimensions of a case, either by the use of dies, or fire-forming. Case reforming is frequently done to make obsolete or hard to get cases, from another which is readily available. A mandatory operation when dealing with wildcats and “improved” cartridges.

Remaining Energy: The kinetic energy, normally expressed in foot- pounds, retained by a projectile at a given range.

Remaining Velocity: The velocity of a projectile, at a given distance downrange.

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.

Rifling: The series of spiral grooves, cut or pressed into the bore of a firearm, intended to impart spin to a projectile.

Rimfire: Any cartridge having its priming mixture contained within its rim. For all practical purposes, rimfires are non-reloadable.

Round: Military terminology for a single, loaded cartridge.

Round Nose: A type of bullet having a blunt, rounded profile. Best suited to short range use, due to its poor ballistic shape.

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Sabot: Literally, a French word meaning “shoe.” In weapons systems, sabots are a device used to center a sub-caliber projectile in a bore for firing. The sabot normally disengages from the projectile shortly after it exits the muzzle, falling to rest a short distance in front of the gun.

SAAMI: Sporting Arms and Ammunition Manufacturers Institute.

Seating Depth: The depth to which the base of a given bullet is seated below the case mouth.

Sectional Density: A bullets weight, in pounds, divided by its diameter in inches squared. High sectional density is essential to producing a good ballistic coefficient and deep penetration.

SEE: Abbreviation for Secondary Explosive Effect. SEE is a condition which can occur when slow-burning powders are used at greatly reduced charge weights (poor loading density). Rather than burning in a normal fashion, the powder detonates, as though it were a severe overload. Also known as a “pressure excursion.”

Selective Fire: The capability of some automatic weapons to fire in either the automatic or semi-automatic mode at the firer’s discretion. These weapons normally have a switch or selector lever to facilitate the operator’s choice.

Shell Holder: The piece of a reloading press which holds the base of the case during the reloading process. Shell holders are generally removable, allowing one press to reload a wide variety of cases by changing to the appropriate one.

Shoulder: The sloping portion of a cartridge case, located between the neck and the case body.

Single-Base: Any smokeless propellant which uses nitrocellulose as its only explosive base. Refer to: Smokeless Powder, and Double-Base.

Slam Fire: A slam fire is an accidental discharge that occurs during the feeding cycle, with no action on the part of the shooter. Most frequently associated with Service Rifles in combination with poorly assembled ammunition. The most common cause in handloaded ammunition is 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.

Smokeless Powder: A propellant powder, composed primarily of nitrocellulose (single-base), or nitrocellulose and nitroglycerine (double-base). There are triple-base powders as well, but they are not used for reloading here in the U.S. Smokeless powder comes in several forms, such as extruded tubular, ball, and flake.

Spherical Powder: See: Ball Powder.

Spire Point: A conically pointed bullet, as opposed to the more common radiused ogival nose shape.

Spitzer: Literally, German for “pointed.” In weapons terminology, a spitzer refers to a pointed bullet.

Sub-Machine Gun: An Automatic or Selective Fire weapon chambered for a pistol cartridge. These weapons are normally compact, and intended to be used at close combat ranges.

Swage: To form metal under pressure. Normally done in a press, using a punch or die.

SWC: Semi-Wadcutter

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Terminal Ballistics: The branch of ballistics which deals with the projectiles impact on target.

Throat: The unrifled portion of the bore immediately ahead of the chamber, and before the leade. Also referred to as freebore.

Time Of Flight: The time taken by a projectile to traverse two points, or a specific distance. Time of flight is a critical factor to a number of ballistic calculations.

Trajectory: The arched path that a bullet follows in flight. Refer to: Bullet Path.

Twist: The rate at which a firearms rifling turns within the barrel. This is normally expressed as the distance required for the projectile to make one complete revolution. Depending on the origin of the firearm, this may be written in inches or in millimeters; 1x12" or 1x305mm.

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USPSA: United States Practical Shooting Association

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Varmint: A non-game animal such as coyotes, woodchucks, or prairie dogs. In many states, varmints are not protected with regard to seasons or bag limits.

Varminter: Sierra’s designation for a line of frangible bullets, intended for varmint shooting.

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 Remington or the 22-250.

Velocity: The speed of a projectile, usually expressed in feet per second at a given distance.

VHA: Varmint Hunters Association

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Wadcutter: A bullet having a full-caliber flat nose, intended to cut a clean hole in the target for easier scoring.

WCF: Winchester Center Fire. Designates a center fire cartridge designed or produced by Winchester. Examples would include the .30 WCF (.30-30), .38-40 WCF, and .44-40 WCF.

Web: The solid portion of a cartridge case between the primer pocket and the powder chamber. The primer pocket and powder chamber are joined by the flash hole, or vent.

Wildcat: A non-standard cartridge or chambering. While the distinctions are somewhat blurred, “wildcat” generally refers to a cartridge for which factory chambered guns and factory loaded ammunition has never been produced.

Windage: Lateral correction of a firearms sights, to compensate for the projectiles deflection by wind or drift.

Work Hardened: To have changed the grain structure of a metal by repeatedly stressing it. In cartridge cases, work hardening most frequently occurs in and around the neck area, from the stresses of repeated firings and resizings. This causes brittleness, and leads to cracking and splitting of the case.

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X-ring: The small center scoring ring in a target. The numerical value of a shot in the x-ring is the same as the highest scoring ring on the target, but is used to break ties.

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Yaw: The rotation of a bullet at an angle (usually very slight) to its line of flight. Some yaw is almost always present when a bullet is fired, but this usually dampens out within 200 yards if the bullet is properly stabilized and well balanced.

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Zero: The adjustment of a firearms sights in order to obtain impact at a desired point in relation to a specific point of aim, at a given range.

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