So I've made a few catchboxes thus far... Some work better than others. I can't figure out why I'm getting ammo bounce back in some setups. I keep plenty of cloth loosely hanging, in two layers - a lighter first layer and a heavier towel at the back (plus a hard backstop). I'm shooting 6mm steel with a very light setup, so very low energy. The shots are bouncing back without hitting the backstop. I understand that it might be inevitable that some shots will bounce back and out of the catchbox - is there a way to minimize this? Is my cloth too heavy? Thanks for the input!