I think it is no like a situation in software patents. AK-47 is an unique machine gun, patents do not protect the general principles, but the way it is made, the system it use and some unique technologies. It is like smbd copies BMW. Copies completely, and then says "Hey, all the engine technology is known, and all the other stuff, why can't I do it" All such talks about patents especially in the military sphere are bullshit (sorry for that), there are a lot of military secrets, which can not be patented due to th fact they are secret. Sorry for my English