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-107 AK-107 The AK-107 is a Russian 5.45×39mm assault rifle developed from the AK-100-series. It features a "balanced" operating system, similar to that used in the AEK-971. In this case, the designation AK does not indicate "Avtomat Kalashnikova" but "Alexandrov/Kalashnikov". The revised designation indicates the incorporation of a new gas system, designed by Youriy Alexandrov, for Kalashnikov-pattern rifles. These new rifles were derived from the AL-7 experimental rifle of the early 1970s. The AL-7 utilized an innovative balanced gas operating system known as the Balanced Automatics Recoil System (BARS) developed by Peter Andreevich Tkachev of TsNIITochMash that was first used earlier