To the Russians credit, they were and still are excedingly good at copying technology. The sovets on the other hand many problems stemming from the communist system such as, very poor quality control, and not rewarding innovators.
They did have on the other hand a really good rifle. The AK47 will fire in almost any conditions under any circumstances. I have heard of AKs being buried in rice paddies for over a year , pulled up, and drained out, still functioned properly. My buddy who was in afghansistan, they found an AK that the bolt had rusted shut on. They used a Gerber to pound the bolt back in order to rack it, after they racked it, it still fired.
But Americans, I think have been a little more concerned with accuracy than reliability.