What I would do is get you some cardboard or drop cieling tiles, these work best. Take a 2x12 and some allthread and sandwich the tiles or cardboard between them start to tighten the all thread tilll compressed and put your taget on it and start shooting. Hay bales won't stop your arrows it just slows them down. If you put one behind the other it may work but you will have to dig your arrow out everytime. I have shot into one of those big round hay bales and it stops them nicely and they are plenty big enough.