Um...look don't take this the wrong way, but I grew up out west and have backpacked all over the west for years. I have seen innumerable black bears in the wild, I have seen a real life grizzly bear while backpacking, I have seen moose in the Sawtooths. Every single bear I have ever seen including the grizzly ran away. I once jumped a mother and her cub. They immediately ran up a tree. The point: the risk of being attacked by a bear or moose is exceedingly remote.
The second point. You ever kill a deer? I have killed a few deer, and antelope...with high powered rifles. They almost never die immediately. Deer weigh 150 pounds.
So the basic idea is --- a bear is going to attack you and you are going to stop it with a handgun. Any handgun. Let me tell you what is actually going to happen. To whatever extent that bear was angry enough to attack you, it is going to be that much more angry after you wound it with your handgun. It may actually enjoy ripping you limb from limb and swallowing your handgun whole. When I saw that grizzly I was carrying my 45 and I remember being in awe at the sheer power of the animal. As it walked (it didn't see me at first) I saw the muscles ripple under the skin. Awesome. I remember having the distinct thought that shooting that thing with my pistol would be about the dumbest thing I could possibly do in that situation.
I knew a hunting guide from Alaska who actually was attacked by a grizzly and who successfully defended himself with a firearm. That firearm was a 375 H&H rifle and he shot the bear in the head. The context of this conversation - we were talking about how dumb it is to think you are going to stop an attacking bear with a deer hunting rifle.
I like guns and I like to carry them when I am outdoors. Handguns are great protection against 2 legged animals that recognize them on sight and are deterred.
The best protection against bears is a clean campsite with your food tied up 20+ feet in the trees and all food and animal waste moved way, way out of the campsite.
If you like 357s (I do) then bring one with you. Just don't delude yourself into thinking that it or any other handgun is going to do jack if a bear attacks you.
My 2 cents...