by only having to resize the neck of the case and to trim-to-length so that the batch performance of the reloaded ammunition is as consistent as is possible from shot to shot. Some competition reloaders leave the primer slightly proud of the case by a known amount that is taken up when the bolt is locked home. This mechanical action on the center of the case base via the primer, as it is pushed a very small amount further into its cup, translates into an even distribution of pressure through the rim to the rim-stop. This also gives the advantage of the firing pin indenting the primer in a similar fashion from shot to shot as the primer cup is in direct contact with the bolt face. As with any reloading all care must be taken and manufacturer's recommendations followed. Headspace actuated blowback An unusual firearms operation has been used, in particular with prototype firearms using headspace as part of its operation. This works with the cartridge moving backwards, stretching it to an extent until it unlocks the bolt to cycle its operation. References External links Cruffler.com article from October 1999 Forster Products article How to measure headspace PDF paper of Armalite.com C.I.P. HOMOLOGATION List of TDCC - Tab I - Rimless cartridges C.I.P. HOMOLOGATION List of TDCC - Tab II - Rimmed cartridges C.I.P. HOMOLOGATION List of TDCC - Tab III - Magnum cartridges C.I.P. HOMOLOGATION List of TDCC - Tab IV - Pistol and revolver cartridges C.I.P. HOMOLOGATION List of TDCC - Tab V - Rimfire cartridges - Crusher C.I.P. HOMOLOGATION List of TDCC - Tab V - Rimfire cartridges - Transducer C.I.P. HOMOLOGATION List of TDCC - Tab VI - Cartridges for industrial use C.I.P. HOMOLOGATION List of TDCC - Tab VII - Shot cartridges C.I.P. HOMOLOGATION List of TDCC - Tab VIII - Cartridges for alarm weapons C.I.P. HOMOLOGATION List of TDCC - Tab IX - Dust shot cartridges C.I.P. HOMOLOGATION List of TDCC - Tab X - Cartridges for other weapons Ammunition Firearm actions