Lots of hot stove talk about shooting big bears...but how much experience?
Funny, my dad spent time in the far north in the '50's, and felt that a 30-06 with 220 grain bullets was more than enough gun to take polar bears, which he did on more than one occasion. The average male goes about 9 feet and 900 pounds - just as big as their brown cousins. He also shot wood bison in the Fort Smith area, and the '06 did the trick on them, too. Anyone using a .300 Win. Mag. with a heavy (200 gr. +) slug shouldn't feel undergunned, especially with the quality bullets we have these days.
That being said, if I was going bear hunting, I'd use my .338 Win. Mag., because I happen to own one. But I wouldn't feel undergunned with my pre-64 M70 30-06 if I happened across a grizz in the pursuit of moose. A distinct possibility where I live.