the nastiest recoil i have ever had was from a old New England Arms sawed off 12ga. of my grandpaws. the thing had about a 18 inch barrel, a nearly staight stock and wieghed less than 5 lbs.
I put a 3" 00 buck in it and when i pulled the trigger it unhinged my sensess for a few seconds and left me bleeding and holding the forarm in one hand and the stock in the other. the breech lock behind the hammer drove through the webbing beside my thumb wich unlocked the barrel during recoil causing me to snatch the forarm off while stumbling backwards and the barrel ended up on the ground
, After i collected myself i put the gun back together put it back in poppas gun cabinit and never shot it again. that thing is beyond my limits of tolarance