When you're shooting that hardened steel the bullets shatter on impact and go flying in every direction. I've used set ups where the steel is angled towards the ground and on a springs to help avoid fragments ricocheting back. Different calibers have widely varying velocities and mass. I would've guessed that some handgun calibers would go through a silver dollar while most would not. There used to be a show on on Saturday mornings about firearms. At the end there'd be a professional trick shooter that people could write in and give them challenges. There was a guy with a simple re-curve bow that could shoot objects out of the air with it. He got down to a flying aspirin and he powdered it. Not a bottle. One pill. Re-curve bow and arrow. I never forgot seeing that in slow motion. Was it 10k takes and pure luck? We'll never know.