My very worst kicker is an 8-Bore rifle, it fires an 850 gr round ball over 300 grains of FFG Swiss powder at 1400 fps.
The rifle weighs 10.0 lbs even, and IIRC churns out about 190 ft. lbs. recoil energy.
Gunner
I shot this 4 Bore in Australia, it weighted 19 pounds. It was a late 1800's era Bland. It shot a 1500 grain lead ball. It was a pleasure to shoot at 19#'s