The general consensus is ".44 magnum or better" but if you can't shoot it well, why are you carrying it? There is also the old saw to file the front sight down so it won't hurt as much when the bear sticks it in your keester.
In general north of the Alaska range but south of the Brooks range- interior Alaska- a bear that squares six feet is about as big as they come, and this one is experienced enough to stay away from people that smell like gunpowder.
North of the Brooks range you got the big white ones, professionals tend to eschew handguns in favor of rifles and the 12 gauge. South of the Alaska range, where you find the salmon fed brown ones and black ones that can get way over six feet, again professionals tend to eschew handguns and keep their rifles close by, generally .45-70 up to .338 Win Mag.
I stick with a Redhawk in .45Colt, but if I am crossing a mountain range from Fairbanks I have some big heavy hardcast with magnum primers and a snoot full of H-110. In the interior I tend to carry the 270SAA ~BHN 15 clocking 1000-1100ish over a reasonable amount of HS-6.