The .20 BR is a centerfire wildcat rifle cartridge. It is based on the .22 BR Remington case necked down to accept a 5.2 millimetres (0.204 in) diameter bullet and maintaining the shoulder angle of 30° and case length of 39 millimetres (1.535 in). The cartridge features a short fat case which is reputed to be both efficient and accurate. The large powder capacity of the case allows it to propel a 2.6 grams (40 gr) bullet at over 1,200 metres per second (4,000 ft/s), however the cartridge is considered overbore and can be expected to have a relatively short barrel life.