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
AK-47 actually less accurate than the forged/milled receivers of their predecessors: the milled AK-47s are capable of shooting groups at , whereas the stamped AKMs are capable of shooting groups at . The best shooters are able to hit a man-sized target at within five shots (firing from prone or bench rest position) or ten shots (standing). The single-shot hit-probability on the NATO E-type Silhouette Target (a human upper body half and head silhouette) of the AK-47 and the later developed AK-74, M16A1 and M16A2 assault rifles were measured by the US military under ideal proving ground conditions in the 1980s