Actually, in case of Zombies, an AR is my preferred choice. Or gophers & ground hogs. For everything else though, I prefer the goodness of 7.62x39!
Ignore the accuracy hoo ha. It was designed to be "effective" and "reliable." Also - get some good ammo (nothing with an animal name) and see how well it shoots. Corbon or Hornady. That will take an MOA right off the top at least. Sight it in properly also.