Hello from Oregon,

I've come to the conclusion that I NEED another handgun for my rafting trips just in case I come across a bear and I need to protect myself and those on my raft or in the campground or on hikes.  I know that black bears tend to run away fast but maybe if one doesn't run away or maybe if I decide to raft in Alaska near Grizzly Bears what would be the best handgun that would kill that Bear FOR SURE if I had to shoot it?  I've heard that angry bears are pure adrenalin and are hard to stop, heads shaped like footballs so bullets can bounce off, etc. Curious if there is a handgun that will stop them with no problems or do you have to have a guide gun or a rifle?