Cordite

Technically you could call them both the Kalashnikov (both guns where designed by him) but since the 47 was the original design and the most famous that is what is generally thought of as the Kalashnikov. Though both guns are very similar and many parts interchangeable (the 74 being the upgrade) the biggest change is in caliber. The 47 uses the 7.62x39mm (30 caliber) and the 74 is in 5.45x39mm (22 caliber), slightly smaller but faster, more accurate and affected less by trajectory. For this reason ammunition and magazines are not interchangeable (the 74 has polymer magazines). Both would do similar damage at close range though the 7.62 is the more powerful cartridge and has greater recoil making it more difficult to manage under full auto. You also mentioned the difficulty of obtaining a Barrett 50 cal rifle. The only state that has ban the 50 cal is California. For this reason The Barrett Firearms Company has suspended the sale and service of there rifles to California law enforcement out of principle but there is no law preventing them from ownership and the Barrett82 is not the only 50 BMG rifle. I suspect that it would not be difficult for criminals to obtain one (weight and expense make it rarely used in crime) and in might be rather easy for dirty cops. Feel free to email me with any firearms related questions. I don't know everything of coarse but I love to research guns and I've used enough to know a bit =) And thank you for listening. I think you do a pretty good job of making it real and it's nice to see someone who cares about getting it right.