I think it has to do with shooting form, and just relaxing. I shoot a .416 Rigby (CZ 550)off a bench and have shot as many as 40 rounds in one sitting with no problem. I am a large body. I have taught my son and a friend to shoot it and once I could get them to hold it correctly and relax they were very surprised that is was not bad at all. They both shoot short action cal. and are very recoil sensitive. But if you try to stand up to the recoil it will hurt you.
