I guess the biggest thumper I've fired was a borrowed 450 Ackley in a 1917 Rem, probably 9.5 lbs with a 500gr/2250fps. It was unpleasant but not unbearable.
But it really depends what the target is. I fired 4 rounds from an 11 lb 470 at an elephant, and never felt or heard a thing!

SOS