I see & hear this said about Enfields from time to time and all I can say is perception must vary, or maybe folks just aren't keeping the rifle snug against their shoulder, because it doesn't bother me. I have gone upwards of 150 rounds in a morning and don't have any trouble with it. Shooting clays with my Mossy 500 is a lot rougher on me than shooting my 303 but not too many folks complain about 12 gauge, at least not until they get old and arthritic or something.
was shooting off a table one day and bunched up my shoulder but didn't notice it till after the end of the day. That brass buttpad will leave a mark if you don't seat it well.