Originally Posted by Jstrong
What wildlife are you anticipating running into? Outside of grizzly country a good .357 magnum revolver would be my choice for all of the lower 48. Grizzlies would be the only animal you would need anything bigger for IMO,at least a .44 mag or .454 for them. Ruger makes good sturdy all stainless revolvers,they're built like a train and would serve you well as a pack gun or camping gun.
Small, light, 3" 5 shot .357 if you can...
A .357Mag will put down a black bear only with excellent shot placement, something most people can't actually delivery under high stress conditions. The .44Mag is better but still it's a crap shot - two years ago in my neighborhood a local found a black bear in his kitchen. We fetched is .44Mag and shot the bear, who shook it off and left. That poor caliber choice could have cost him his life. For brown bears there are very few handguns that can reliably protect you. When I was younger one of my uncles shot a brown bear 11 times. With a 30-06. While that's rare it's certainly not extraordinary.
To reliably defend against any bears in a high-stress situation where shot placement will be compromised, you need a true big bore: .454 Casull, .480 Ruger (either loaded with hot, heavy, hard cast Buffalo Bore), maybe a .445 Super Mag. For brown bears go bigger - .460Mag, .500Mag or 45-70 (many guides in grizzle country carry 45-70 lever actions, but not "Gov't" models that are considered too low power. They go for the hottest 45-70 loads available. I trust the opinions of these professionals.)