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-12 all of these features. In January 2012, the Russian Deputy Defense Minister announced that the Russian Army would not be buying the AK-12, as they had millions of surplus AK-74 assault rifles and over concerns of the financial state of Izhmash. Despite this, the Russian Ministry of Defence began trials of the rifle on 2 November 2012. It was tested for its effectiveness when exposed to freezing cold, desert heat, humidity, dust and impacts. By 23 November 2012, trials were about 80 percent complete. During these initial tests, the AK-12 was found to have a "range of defects". The specific