I’m going to start off by saying I’m a huge fan of 10mm , I’m also very familiar with big brown bears considering I’ve lived in may parts of the country where they hang out, I personally would not rely on a autoloadimg 10mm pistol
Grizzly bears can’t be clumped into one category, especially in Alaska , inland brown bears are not the same as costal bears, costal brown bears are MUCH bigger than inland grizzly bears even though they are the same species
In Any pistol caliber hard cast is the way to go, that being said any caliber under 44 mag is a game of luck against a Alaskan bear, having personally encountered a few BIG bears I wouldn’t chance luck especially in costal regions
10mm doesn’t deliver the energy needed to reliably stop a grizzly, and that’s all that is going to do the job , energy
Putting multiple inferior rounds on target isn’t always a option as in the case of the guy with the 9mm
I have several friends that are guides in Alaska and a couple that work for Glacier NP in Montana , they have all recently switched from magnum handguns and rifle cartridges to shotguns with slugs
Keep in mind a big angry bear will still be able to easily kill you even if it dies right by your side 3 seconds later