A rimfire is a type of firearm cartridge. It is called a rimfire because instead of the firing pin striking the primer cap at the center of the base of the cartridge to ignite it (as in a centerfire cartridge) the pin strikes the base's rim.
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A rimfire is a type of firearm cartridge. It is called a rimfire because instead of the firing pin striking the primer cap at the center of the base of the cartridge to ignite it (as in a centerfire cartridge) the pin strikes the base's rim.