If you're going to artificially limit your firepower by choosing a wheel gun, your minimum caliber should be .41 mag, IMO. Bullet choice is very important. Hard cast lead or solids like Barnes or Lehigh will not expand too soon and get to vital areas intact, with enough energy. Hard cast lead is not the same as the common soft lead round nose or semi wad cutters, BTW. With only 5 or 6 shots, shot placement and speed on target is critical. Don't try to carry semi concealed, concealed or worse yet, buried in a bag, behind a coat or stuffed into a pocket. Carry like they do in the Alaska bush, out fully in front or side ready for action. Get a trigger job, an RMR and lots of training for sudden snap shots on fast moving targets. Bring a dog to alert you sooner and distract the bear. Many guides in Alaska carry 2 Glock 10mms and their long guns. Bears don't play.