Below is a list of rebated-rim cartridges. Rebated-rim cartridges have a rim that is significantly smaller in diameter than the base of the case, serving only for extraction. Functionally the same as a rimless case, the rebated rim allows a gun to be easily converted to fire a larger-than-normal cartridge, as most of a firearm's loading and extraction mechanism does not need to be altered as long as the rim size is preserved.[citation needed]
Rebated-rim cartridges are known to be used on firearms using advanced primer ignition (API blowback) for its operation, notably autocannons such as the 20mm Becker/Oerlikon series.[1]API blowback firearms have straight-sided chamber walls as possible (and sometimes slightly bottlenecked) to contain the cartridge and allow a deeper chambering.[citation needed] The bolt face has the same diameter as the rebated-rim cartridge as it follows along with the extraction claw into the chambering.[2]
