I'm thinking of building a bullet trap out of everyday A36 plate steel angled from the vertical toward the shooter at 45 degrees. How thick would it have to be to tolerate 10mm, .45 Auto, and .44 Magnum for thousands and thousands of hits? If the frame that holds the plate lets it move some, will that make it last longer? The weight difference between 3/8" and 1/2" could be important here.