About ten years ago I belonged to a gun club that had a steel plate to shoot at on the 100 yard range. It was 10" in diameter and 1/2" thick. It was welded to a collar that swung on a horizontal pipe. Many of the people who belonged to the club would save the last 3 or 4 rounds for the plate, shooting off-hand. It was amazing how that heavy piece of steel would swing when hit with a .375 H&H or heavier.