Shotgun. Loaded with full caliber slugs, none of the saboted frilliness, if you want to scrape up every erg of power and aren't worried about range.

Handguns, until you get into the monster stompers starting with .454, just don't do much to bear. I'm assuming your concerns involve the bear being unhappy with your existance already. Hunging them is another matter- you catch them when they are mellow and eating and just minding thier own business, so you have time to get a good shot off. Pistols are handy, but they don't have the energy you want with a ticked off bear. An animal that is angry and gets hurt gets angrier, in my experince.

If you REALLY need to go with a handgun, you are close with the .45, but I might suggest tradding it in for the compact 10mm that Glock used to make if you want to stay with an autoloader. (Don't know if they still do.) Load it with the heaviest FMJs you can find that are at FULL pressure, not the FBI's "not a .45 but acts like it" pressure level. Aim for the head. Maximum pentration of the brain pan, and repeat it. A lot.

Save the last one for you.

If you don't mind a wheelgun, lots of options. The .454 might give you the most versatility and availability of ammo, but expect to shell out the big bucks for your practice. The .480 from Ruger has a slight edge. 357 and 44 Magnums can do it, but again, I'm assuming the bear really would like to see you in parts and you want to make sure that doesn't happen.

I've seen what black bears can do to plywood and 2x4 garbage bins. Thats just being hungry. Being really, really pissed, I wouldn't want a pistol, myself.

I can't comment on hogs, never been around them, other than to say that they have a reputation for being ornery and stubborn. Again, I'm not sure I'd put my faith in a handgun.