I used to shoot in my garage years ago, I taped an A4 sheet on to the concrete panel but on the rifles approaching the legal limit, Bits of lead used to come back the twenty five feet and hit me on the forearm or on the face so I started saving the massive soap powder boxes that the wife used and stuffing them with old newspapers!, No more pain!!When neighbours are not happy when they hear the whistle-thock of shooting a stack of magazines or thick catalogue, a really good alternative can be had with putting layers of old carpet in a box. I have a 12 x 14 inch box, with a layer of 9mm OSB at the back, and a stack of cut carpet squares totaling three to four inches thick. I have some wood strips across the front that both keep the carpet in place and give me somewhere to tape targets to. After a while the top two or three layers of carpet get chewed up and need replacing, but that is the same with shooting old phone books too.