They are as good as you are, if you are accurate enough to hit a rabbit, squirrel or pigeon etc in the head at 10 yards the catapult will kill it. if you cant shoot as well as that do NOT hunt with it. You will also need to use either lead or steel ball bearings and NOT stones. You can use the steel 9mm BBs but they are really too light for hunting, lead is better but you have to make your own which is a pain.
For practice, until you are good enough to hunt, hang a sheet up as a back stop. Make sure there are a few folds on the groung to catch the ammo ang put a target up in front. Once yo