My first .460 was before they ported them & I just went to my bench & started to shoot. 6 rounds later I was seeing black with shiny stars flickering. The moral is....don't shoot a ball buster with it low on the table & you leaning into it. Have it hi enough to sit up straight & don't lean in, just have it snug to shoulder.
But, the all time worst was my first .470 double. It was a Douglas & it just did not fit right for me & about broke my shoulder, it really hurt.
For sheer snap from an overbore, the .378 Wby w/o break, no doubt. Even with the break it'll get your attention.
ps it took 2 wks before the stars went away