The .222 rimmed / 5.7x43mmR is an intermediate centrefire rifle cartridge, originating in Australia in the 1960s as a cartridge for single shot rifles, particularly the Martini Cadet action.

[citation needed] Performance is similar to the .222 Remington on which it is based however loads should be reduced as the walls of the brass cases are generally thicker.

[2] Extraction of cases that have been loaded to higher pressures can be difficult due to the inefficient extraction method utilised by the Martini Cadet.

Cases and loaded rounds were originally produced by the Super Cartridge Company.

[3] Brass is now available from the Bertram Bullet Company[4] or can be made from 5.6x50mmR RWS cases.