I've never tried to shoulder shoot a punt gun!
My 50 cal. Lyman GPR will bite my shoulder with just 70 grains of 3fg. I load 60 grains for target shooting and wear a PAST pad for hunting loads. The but plate on those rifles is designed to hurt you!
The hardest kicking thing I will shoot on purpose is my 870 three inch mag loaded with 2 ounce turkey loads. Even with a good recoil pad and three ounces of lead added to the stock, it's more than I enjoy.
The worst beating I ever took from a gun was goose hunting in rice fields with my Red Label and three inch magnum loads. It was fun the first day.