Well as long as the thing your trying to kill is at least 5-10 meters in front of you, no matter what its going to be shredded whether its a zombie or a fricken bear(well i dunno bears are pretty beast).In other words if your in a hallway or indoor areas you pretty much got no chance of missing,i mean you wouldn't fire a sniper if your raiding a house unless your just a ridiculously amazing shot.
Then again i've never fired a proper gun as of yet so regard my information completely theoretical.Oh yeah and this.