Rick,
I had a 416 Rigby that my son could shoot off the bench round after round without saying a word. First time he shot the Zim he fired 3 rounds and then one more and then handed it back and he also used the the term SOB. smile Whenever anyone asks to shoot it I just tell them hang on tight and don't drop it. Then I smile.
There are certainly bigger and more powerful cartridges but the Zim is a sharp sharp crack when it recoils. A 416 although heavier in total recoil, it is a much easier push.