I'll start by saying I have a Rossi 92 20" barrel with the "C" shaped steel butt plate. I just bought a life time supply of RD 290 gr bullets and I've read they are painful which I believe beyond a doubt. Now due to the fact I use this gun also in cowboy action shooting which means no butt plates other than a leather cover so no permanent modifications allowed. So hear is what I've come up with to use for hunting with these heavy loads.
I'm think of taking a slip on type limb saver can cutting it to fit the "C" shape of the butt. At this point I also don't want to add much length to the stock either so figured I would square it off (or leave it flat) then sew it into a leather strap on type cover. It would give a look similar to say a 454 92 in the shape of the butt. My only doubts are on the corners of the "C" as there it would be the thinnest padding. Any input on this would be appreciated as I know someone that can do the leather work but would need to get an idea of the thickness of padding it would need.
Picture below is a quick sketch where the gray would be the cut pad that would be held in place by the leather.