Right, with the proper training and practice, a rifle can certainly be the better weapon. But on the show that's not really feasible. They mostly stick with the sidearms they constantly have on their belts. Sure they are a little too good with those (like how does Rick hit anything in the head with his Python
) , but I didn't feel them not being able to hit anyone with the auto rifles was unbelievable.
But in general, full auto rifles aren't that great. Fun to shoot, but not very practical for accuracy. Only when playing a video game is a fully automatic weapon very accurate