There are two schools of thought on this. Some guys prefer a really large revolver, like a 500S&W. Much heftier, so when you're empty and throw it at the bear, you have a better chance of braining him. Thriftier guys, who hate throwing away a perfectly good, if useless when empty gun, opt for 44 magnums, especially very lightweight revolvers like the 329PD. Slows you down much less when you're runing for your life.