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-74 AK-100 series and RPK-74M than the earlier prototypes and the arms manufacturer Kalashnikov concern hopes they will replace these Russian service guns. In late 2016 it was reported the AK-12 production model was undergoing troop trials with the Russian Army, where it competes against the Degtyarov A-545 balanced action assault rifle in Ratnik program trials. The AK-12 completed its operational testing and passed military field tests in June 2017, paving the way to Russian Army adoption, potentially under the Ratnik program. Both AK-12 and AK-15 completed testing in December 2017. In January 2018 it was announced that the AK-12 and