When I was a kid, a buddy had a H&R 10ga single shot he would take duck hunting. No recoil pad, I think the screws were stripped out. Don't remember what load he was using, but it kicked the snot out of you. I'll never forget the huge black and blue mark on my shoulder after we shot a box of shells at tin cans, practicing. He sold it the next season and got a pump 12ga - smart kid...lol I have shot a lot of other heavy kickers, but with recoil pads, and proper fitting stocks that don't punch you in the jaw, and allow you to roll with the kick.
Larry