Alright here's how I see this. The other day Aaron went out and shot a friends AK and he brought it home for me to clean. The day they shot it it worked GREAT not the most accurate gun but still wonderful. While I was cleaning it I pulled ROCKS out of the top of the recoil spring. It was so filthy that it was like changing the oil in a car and there was mud all around the barrel. THE THING WAS STILL SHOOTING!!!!!!!
On the other hand I have a bushmaster AR 15 NEVER had a problem with it, but it is cleaned quite frequently and I have never given it the chance to get dirty and see what it can do, but I (having only shot for about 3 years now) Can shoot quarter inch groups with it at over 100 yards (for exact yards I will have to have Aaron remind me I have the worst memory) so as far as accuracy goes AR 15's are wonderful.
Not all of us are trophy hunters.