Just my thoughts and maybe something a little unique: I've travelled almost the entire interior of AK and just about everywhere in the Lower 48 where Grizzlies live and I've done my research on dangerous game. My personal solution is the Glock 20 in 10mm or the Glock 21 (45 ACP) and Pepper Spray. First, the gun is a noisemaker for a bear that is in the vicinity that hasn't charged or made an indication that he or she will. That's the pistols greatest succes that no one really talks about: shear noise that can prevent a lot of trouble.
In a charging situation I'd go for the pepper spray first. The odds are much higher and stopping a charging bear with a pistol maybe only increases your odds from none to slim (and that's being optimistic) whereas the pepper spray has over a 90 percent success rate.
And in the worst case, if the bear gets on top of you the pistol is still a possibility whereas a rifle or shotgun would now be useless (two game wardens in MT have proven this by shooting Griz of the top of themselves in separate instances each with a 357 mag). I know the 44 is more powerful, but the Glock carries a lot more so you can waste one or two as noisemakers and still have plenty left. The 10mm or the 45 is more powerful than the 357 and the extra shots will more than make up for what is lost from the 44. Additionally, the Glock is perfectly safe with one in the chamber and as dependable as anything in my experience and in all of my research as well.
The only catch to the system is you have to be decisive on which you are going to use and when and be able to stick to those decisions. I'm simply trying to stack the odds the best I can, and hopefully I never have to test my little system. But that's the bummer of bear problems: the odds are extremely slim, but the consequences can be severe.
Note: I have switched to the 45 ACP (still a Glock) and have edited this post.
However, I'm still not entirely convinced that the 44 mag or one of the new "hand cannon" calibers isn't the best way to go for Griz. It's all a matter of opinion and there are good sides and bad sides to both.