Firearm a battle rifle such as the Karabiner 98k, but the chief differences defining an assault rifle are select-fire capability and the use of a rifle round of lesser power, known as an intermediate cartridge. Soviet engineer Mikhail Kalashnikov quickly adapted the German concept, using a less-powerful 7.62×39mm cartridge derived from the standard 7.62×54mmR Russian battle rifle round, to produce the AK-47, which has become the world's most widely used assault rifle. Soon after World War II, the Automatic Kalashnikov AK-47 assault rifle began to be fielded by the Soviet Union and its allies in the Eastern Bloc, as well as
AO-63 assault rifle AO-63 assault rifle The AO-63 () is a Soviet two-barrel AK derived assault rifle chambered for the 5.45x39mm round. It was designed by S. G. Simonov and P. A. Tkachev, and manufactured by TsNIITochMash. It uses a side by side barrel configuration, and it can reach a maximum rate of fire of 6000 rounds/min when fired in two round burst mode with a 0.01 millisecond delay to increase ballistic performance, making it the fastest firing assault rifle known. The AO-63 assault rifle was used by the Spetsnaz during the Abakan trials in May/June 1986, in search of a more accurate