Straight from the manual, "The Winchester Wildcat rifle must only be used with 22 Long Rifle rimfire ammunition as designated on the barrel. Do not shoot 22 Short or 22 Long ammunition, blanks or bird shot cartridges." Any idea what that is? I called Winchester and really didnt get an answer out of the guy...just that you can only shoot whats on the barrel. I asked him if it was just because of the magazine, Could I single load them? He said well the shell size is different. I said ok, figured i would call again and see if I got someone else there.