Shotgun shell

A shotgun shell is a self-contained cartridge typically loaded with multiple metallic "shot", which are small, generally spherical projectiles. Traditionally lead was used, but increasingly steel, tungsten or bismuth shot has replaced lead, due to laws designed to protect the environment. A single, large projectile known as a shotgun slug can also be used, and numerous specialty rounds such as less-lethal rounds (e.g. beanbag rounds), flechette rounds, lead-dust rounds for door-breaching are also available. An old non-lethal shotgun load consisted of a shotgun shell loaded with rock salt, which could inflict very painful, but rarely deadly, wounds, and was therefore popular for scaring away trespassers.

Most shotgun shells are designed to be fired from a smoothbore barrel, but dedicated shotguns with rifled barrels may take a number of different rounds. A rifled barrel will increase the accuracy of slugs, but makes it unsuitable for firing shot, as it imparts a spin to the shot cup, causing a centrifugal force that makes the shot cluster disperse.Specialty shotgun ammunition includes non-lethal rounds available in the form of slugs made of low-density material, such as rubber.

Early shotgun shells used brass cases, not unlike rifle and pistol cartridge cases of the same era. These brass shotgun hulls or cases closely resembled rifle cartridges, in terms of both the head and primer portions of the shotgun shell, as well as in their dimensions. Card wads, made of felt, leather, and cork, as well as paperboard, were all used at various times. Waterglass was commonly used to cement the top overshot wad into these brass shell casings. No roll crimp or fold crimp was used on these early brass cases, although roll crimps were eventually used by some manufacturers to hold the overshot wad in place securely. The primers on these early shotgun shells were identical to pistol primers of the same diameter.

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