I would choose a powerful handgun, but one that I could shoot accurately and practice with regularly. Some, like jcb9901 can handle a .454 with confidence. Most of my friends that bought .454 Casulls or .475 Linebaughs are intimidated by their guns. Hence they seldom shoot these cannons and they are not likely to be competent in the event a bear charges. One of my buddies that fishes Alaska a lot bought a double action Smith and Wesson Mountain Gun in .44 Magnum. He loads it with heavy 305 grain hard cast bullets from Buffalo Bore (1325 ft./sec., ME 1189 ft. lbs.) when he's in the river, but practices regularly, double action style, with less expensive loads so that he is proficient in getting the gun out quickly and getting off several accurate shots.

Pick ammo that will penetrate. The usual expanding jacketed hollow points and soft points loaded in factory rounds in most .44 magnums,and even in some .454 and .480s often fail and flatten out on the skull or shoulder bones. Quality hard cast bullets or heavily constructed full metal jacket bullets with a flat nose, essentially solids, can reliably penetrate grizzly skulls or reach into the heart and lung area.

Picking out a new gun is such a kick. Have fun and good luck in Alaska.

Doug