Backlash - The distance the trigger travels after let-off.

Baffles - Barriers to contain bullets and to reduce, redirect or suppress sound waves. Baffles are placed either overhead, alongside or at ground level.

Ball - In military nomenclature this term refers to the bullet.

Ball Ammunition - General-purpose standard service ammunition with a solid core (usually of lead) bullet.

Ball Powder - A propellant with spherical granules, usually denser than extruded powders, hence better for small cases. Developed by Western Cartridge Company around the start of World War II.

Ballistic Coefficient ( BC ) - A mathematical factor representing the ratio of the sectional density of a bullet to its coefficient of form.  Simply put, BC expresses a bullet’s length ( relative to diameter ) and aerodynamic shape, thus indicating its ability to overcome air resistance in flight.  The higher its BC factor, the better a bullet retains its velocity and energy, and the flatter its trajectory.  Most bullets have BCs between .100 and .700. Higher BCs are required for long-range shooting.

Ballistics - The science that deals with the motion and flight characteristics of projectiles.  It can be divided into three phases:
    1) Internal ballistics
    2) Exterior ballistics
    3) Terminal ballistics.
The main aspects of ballistics that concern the rifleman are bullet velocity, stability, kinetic energy, trajectory and penetration/wounding effect.

Barrel - That part of a firearm through which a projectile or shot charge travels under the impetus of powder gases, compressed air, or other like means. May be rifled or smooth-bore. See Rifling.

Barrel Band - Metal band that secures the barrel to the fore-end of a full-length rifle stock.

Barrel Erosion / Barrel Wear - The gradual eroding away of the rifling lands immediately ahead of the chamber throat, resulting in accuracy loss. Metal surface is burned away by the intensely concentrated powder flame at this point.

Barrel Liner - Thin steel tube usually permanently inserted into the barrel to either change the calibre, restore the gun, or to make the gun more functional when the barrel is formed from softer material.

Barrel Time - The interval between the time the bullet starts to leave its seat until it reaches the muzzle.  This is significant because is it linked to recoil time, which affects the point of impact.  See Recoil, Point of impact.

Barrelled Action - A combination of barrel and receiver or frame and breech bolt, together with the other parts of the mechanism by which a firearm is loaded, fired and unloaded.

Battered Cartridge - The cartridge is deformed in such a way that it will not chamber in the rifle.

Battle Rifle - Term still used to represent any full size caliber rifle as opposed to a assault rifle cartridge like the .223 or 7.63x39mm. A Main Battle rifle is one designed to fire a full powered cartridge like the 30-06, 8x57mm, 7x57mm and even the 7.62x51 Nato. These rifles are generally large, heavy, and have excessive recoil. The term differentiates them from assault style rifles designed to fire short, light weight and low recoiling rounds.

Bead Sight - The small cylindrical top portion on some forms of front sights.

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

Beat - The sniper's operational area where established control measures (boundaries, limits) define his territory.

Beavertail Fore-end - The forward part of a one-piece stock. (Shotgun) a larger, wrap-around forearm as opposed to a "splinter" forearm. Also called forearm.

Bedding - Refers to the fit or fitting of the metal parts of the barrel and receiver with the wood stock.

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 "rimless" cartridge case with a raised integral belt around the case just ahead of the extractor groove to provide a positive headspacing surface while retaining the extractor groove ( which facilitates use in Mauser actions ). This type of construction is generally used on large capacity magnum-type cartridges. See Headspace, Magnum, Rim. ( Click here for picture. )

Benchrest Rifle - A rifle designed for optimum accuracy while being shot from the shoulder and supported by a specifically designed table (rest). Shooting event utilizing rifles and ammunition designed to deliver extreme accuracy at long ranges.

Berdan Primer - A primer containing no internal anvil. In the Berdan system, the anvil is an integral part of the cartridge case, formed by a conical projection rising from the floor of the primer pocket, and flanked by ( normally ) twin flash holes. Berdan cases are not convenient for reloading, as depriming requires special equipment and is time-consuming. Some claim this to be more accurate, since the twin flash holes ensure more even ignition of the powder.

Berm - An embankment used for restricting bullets to a given area or as a dividing wall between ranges. Also backstop, baffle.

Bipod - A two-legged support attached to the fore-end of a rifle, used mainly for long range and/or accurate shooting. ( To read some reviews, click here. )

Black Powder - The earliest form of propellant, characterized by the huge cloud of white smoke produced. It is reputed to have been made by the Chinese or Hindus. First used for guns in the 13th Century. It is a mechanical mixture of potassium or sodium nitrate, charcoal and sulphur. High in saltpetre, hence extremely corrosive to barrels if residue is not immediately cleaned out. Replaced around the turn of the century by the cleaner and faster-burning “smokeless” propellants. It is still used by antique firearm (or replica ) enthusiasts. A low-pressure propellant: the firearms were not as strongly built as modern ones, hence should not be used with nitro powder/ammo.

Blackout - Condition where the exit pupil of a scope is smaller than the pupil of the shooter, which results in the target image forming on only part of the eye, with a surrounding black ring. This makes it more difficult to focus on the target. See exit pupil.

Bloop Tube - It is a tube, with over-calibre inside dimensions, added to the front of a barrel to extend the sight radius.  Normally used in target shooting with short-barrelled weapons.

Blown Primer - Where the primer has fallen completely out of its pocket when the cartridge is extracted after firing.

Blue - The chemical oxidation to colour ferrous metal parts various shades of blue or black.

Boat Tail ( BT ) - Bullet of tapered base or truncated conical base design, which raises the ballistic coefficient factor by reducing the aerodynamic drag, providing greater stability at subsonic velocities. Drag partly comes from the effects of cavitation (turbulence) and the progressive reduction of the diameter toward the rear of the bullet allows the air to fill in the void.  Originally designed for extreme range machine guns barrages, boat tails offer some ballistic advantage on the target range at 800-1000m, as most match-type bullets have boattails to help flatten trajectory.  They have little practical use at shorter ( LE/hunting ) distances, as few modern cartridges drop below the speed of sound at these shorter distances.

Bolt Action - A firearm in which the breech closure is: in line with the bore at all times; manually reciprocated to load, unload and cock; and is locked in place by breech bolt lugs engaging abutments usually in the receiver. There are two principle types of bolt actions, i.e., the turn bolt and the straight pull type.

Bore - The interior of a barrel forward of the chamber.

Bore Diameter - Internal diameter of a barrel measured from the tops of diametrically opposed lands, i.e. the smallest internal diameter.  If the lands are not opposed, the diameter of a circle inscribed to touch the tops of the lands.  It is the inside diameter of the barrel before the rifling is cut.

Bore Sighting - A method of aligning a barrel on a target by aiming through the bore. May be part of the sight alignment procedure. When sighting in a scope tools like a collimator can be used.

Bottleneck Case - Cartridge case with a neck diameter smaller than its body diameter, hence creating a shoulder. ( Click here for picture. )

Boxer Primer - Primer with a 3-legged internal anvil, permitting use of a single, central flash hole in the case head. Such cases can be conveniently deprimed by means of the decapping pin in standard reloading dies.

Brass - Slang for cartridge cases.

Breaking In a Barrel - Process of initial use of a NEW rifle/barrel, by alternately firing and cleaning, a progressively larger number of shots, until a certain number has been reached. This process must be completed before load development for the rifle is started, and/or before the rifle is sighted in for a specific load. One such process is as follows: - Clean before firing - Clean after every shot (w/o the bore brush) for the first 10-20 rounds - Clean after every 5 shots for the next 20-40 shots. - Clean after every 10 shots for another 20-40 shots. - Shoot 20 shots without cleaning before sighting in for good. I've seen a few other methods with different progressions in the number of shots/cleaning. I don't think it matters exactly.

Breech - The chamber end of the barrel.

Breech Face - The part of the action which contacts the rear of the cartridge; the rear end of the barrel.

Bull Barrel - A firearm built with an extra thick walled barrel that adds weight to the muzzle and reduces recoil. Used primarily for target shooting or varmint hunting.

Bullet - The object which is propelled towards the target. This term is often incorrectly used to describe a loaded round of ammunition (cartridge). The ensuing confusion has led to the use of the superfluous term “bullet heads”. The design of the bullet differs for various applications.

Bullet Drop - Term used to describe the measure of a bullet’s fall after it crosses the line of sight for the second time, i.e., beyond the zero or sighted-in range, due to the effect of gravity.  ( Click here for picture. )

Bullet Drop Compensator - Any device that is integral to the rifle telescope that is designed to compensate for the bullet's trajectory.

Bullseye - In target shooting, the aiming point or center of the target.

Burning Rate - Rapidity with which a powder burns, relative to other powders. The burning rate will dictate the type of firearm it can be used in, as well as the application.

Butt - (Handguns) Bottom part of the grip. (Long Guns) Rear of shoulder end of stock, which rests against shooter’s shoulder.

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