the projectiles and propelling charges used in small arms, artillery, and other guns. Ammunition size is usually expressed in terms of calibre, which is the diameter of the projectile as measured in millimetres or inches. In general, projectiles less than 20 mm or .60 inch in diameter are classified as small-arm, and larger calibres are considered artillery. A complete round of ammunition consists of all the components necessary for one firing of the gun. These normally include a projectile, the propellant, and a primer that ignites the propellant. Other components such as cartridge case, fuze, and bursting charge are frequently included.
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