There are a number of places on the internet where you can order steel plates in different sizes and shapes that are made out of AR500 steel. I own quite a few and I can tell you that they will stop anything you shoot at them short of a canon shot. They come in thicknesses of 1/8", 1/4", and 1/2". After thousands of shots they don't even have dimples on them. I used to use just mild steel and even .22lr will dimple these and bend them over time. I had a complete set of Sportsman's Team Challenge targets made out of this mild steel and after a few months on constant shooting the entire 4'x8' (feet, not inches) sheet of steel was getting bent into a curve! I've let rifle shooters shooting .243, 22-250, 308, etc shoot at my AR500 targets @ 1/4" and not even dimple them at 100 yards. Note: dimpled steel targets are, or can be, dangerous. Over the years I've seen some pretty nasty wounds from bullet fragments coming back and hitting the shooter or a spectator from a distance of twenty-five to fifty yards and cause significant injury. I once saw the range master take a 38Super slug into the face and lodge inside his sinus cavities. He needed surgery to get it out. I myself once had a large piece of 45acp return from fifty yards and hit me in the chest and leave a large laceration. Regardless of what anyone tells you on the internet, mild steel can cause serious injury. Get some AR500 targets and enjoy years of shooting with a high degree of safety. Anyone else using mild steel isn't avoiding injury.....it's not "if" , it's WHEN.