You can argue that the first assault rifle appeared in California in recent decades because it s the first time there was a legal definition of what assault rifle actually meant Otherwise just what do we mean by the term Invented In service In bulk service With the performance of a military rifle As there aren t many of such really just the AK47 AKM in full calibre and that s a short intermediate cartridge as it s hard to control most are about 23 calibre rather than 303 But how small can it go and still be a rifle rather than a sub machine gun The Avtomat has the problem that it s using a pretty useless cartridge giving it the performance of a machine pistol Nor can it use anything more powerful owing to the overheating problem Mostly though it s just the limited numbers made 100 as many Sturmgewehr than Avtomat I would disagree Thomas point that the Avtomat cartridge is too large as the 6 5 Arisaka cartridge is so low powered even though it s a large case