My 500 Jeffrey shooting 600 gr bullets. I still haven't worked up to a max load as the 2200 fps starting loads got my attention and then some off the bench.
I'd say once you get to pushing a 500gr or heavier bullet 2200 fps or faster, you're in a different ballpark of recoil compared to lesser rounds. Even though you can concentrate and not flinch, and with proper technique they won't hurt you, but it takes a tremendous amount of concentration to squeeze off each shot because the gun is going to come back hard.
I loaded 350's @ 2400 fps out of my 458 lott and it was downright reasonable, once I even fired off 2 boxes of ammo during a lunchtime range session. But the 500 gr loads, 10 shots in a session was often too much.
