at boot camp, pretty much everyone that qualified sharpshooter or expert (top two qualification tiers) was able to hit at 500 yards, all day long. bear in mind that was known distance, with wind socks and a "dope book".
you could probably hit at 500 yards with an AK, under similar circumstances and with good quality ammo, but not with anywhere the level of consistency you'd find with an AR, M14, or Garand. your AK odds would probably improve if you used 7.62x54, 5.56x45 or (maybe?) 5.45x39, and peep sights, with a longer sight radius (can anyone say "Galil"?).