Centerfire ammunition

A centerfire cartridge is a cartridge with a primer located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component.

Centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes. With the exception of a few .17 caliber and .22 caliber pistol and rifle cartridges, small-bore shotgun cartridges (intended for pest-control), and a handful of antique, mostly obsolete cartridges, almost all pistol, rifle, and shotgun ammunition used today is centerfire.

Advantages

Centerfire cartridges are more reliable for military purposes because the thicker metal cartridge cases can withstand rougher handling without damage, and safer to handle because explosive priming compound in a protruding rim is more likely to be detonated by impact if a rimfire cartridge is dropped or pinched. The stronger base of a centerfire cartridge is able to withstand higher pressures which in turn give a bullet greater velocity and energy. While centerfire cartridge cases require a complex and expensive manufacturing process, explosive handling is simplified by avoiding the spinning process required to uniformly distribute priming explosive into the rim because of uncertainty about which angular segment of a rimfire cartridge rim will be struck by the firing pin. Larger caliber rimfire cartridges require greater volumes of priming explosive than centerfire cartridges, and the required volume may cause an undesirably high pressure during ignition. Reducing the amount of priming explosive would reduce the reliability of rimfire cartridge ignition, and increase the probability of misfire or dud cartridges.