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A center-fire (or centerfire) is a type of metallic cartridge used in firearms, where the primer is located at the center of the base of its casing (i.e. "case head"). Unlike rimfire cartridges, the centerfire primer is typically a separate component seated into a recessed cavity (known as the primer pocket) in the case head and is replaceable by reloading the cartridge.
Centerfire cartridges have supplanted the rimfire cartridge, with the exception of a few small calibers. The majority of today's handguns, rifles, and shotguns use centerfire ammunition, with the exception of some .17 caliber, .20 caliber, and .22 caliber rimfire handgun and rifle cartridges, a few small-bore/gauge shotgun shells (intended mainly for use in pest control), and a handful of antiquated rimfire and pinfire cartridges for various firearm actions.

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