I think the most I could handle, if I ever went on an Alaskan dream hunt for Grizzly, would be the BAR in .338. I'd get it Mag-na-Ported, then it would be sweet. Of course, I'd want an experienced guide backing me up with something nasty and reliable, like the .458 or .416 in a Mauser-style bolt rifle, in case the semi-auto decided to malfunction. I guess a lot of us must fantasize about a hunt like that, or going to Africa for the Big 5. Oh well.......maybe some day, before the old bones get too old...
Something to look into is one of those recoil reducers (I think that they contain mercury, so they're a bit heavy and very expensive). They're really VERY effective.
I used to shoot bowling pin competition, and one guy had a Remington 1100 fitted with one in the stock, as well as being ported. It felt like shooting a very loud .22 rifle! There was almost no felt recoil at all. Now, I realize that the recoil of a 12ga with hot loads of #4 buckshot isn't anywhere near as bad as what you'd get with a big magnum, bit it might be worth a look.
BTW, the guy who owned the shotgun was able to consitantly knock 5 pins off the table in less than 3 seconds (and that includes bringing the weapon up and the last of the 5 pins hitting the ground!)
Mark