Argle. This is one of those ambiguous replies, me not being a bear expert. It seems that bears' weights tend to range mostly from 200 to 400 pounds, from what I read in the huntin' mags. They are a heavier-boned animal than a deer.
So, I'd call a thutty-thutty marginal, at best. Obviously, if the range is inside of fifty yards and your friend is an excellent shot, he'd probably do okay. Some folks are happy with .44 Mag or .45 Colt, with heavy bullets, from what I've read...
I'd rather be over-gunned than under-gunned, since I hate trailing wounded game. I don't want something to get away and suffer. All that sort of stuff.
I'm not about to argue with anybody who's "been there", but my own 'druthers would include an '06 with heavy bullets, or one of the .35s of some sort...