I was helping a friend with his range, he was using these pieces of rubber, he thinks came from 10 ply tires. The pieces were being placed in front of the control boxes at the range. I saw they had deflections on them, so I shot them with what I had with me, I even put them in a go bag and shot them, the picture shows the one I shot, the actual hole you can see is from my rem 870 12 gauge. It didn't puncture as you can see, the other rounds, 5.56 and 40 cal didn't even leave a mark.