the .357 WORTHLESS? Man, you must be the ONLY one that knows anything about guns that thinks that...
I agree with the others that suggest a hardcast, heavy-for-caliber bullet for penetration...... remember, with bears, you would possibly shooting thru a pretty heavy coat of fur before actual damage begins... and the .357 is pretty light for bears, so the more penetration you get, the better.
I also would not suggest using a handgun smaller than .44 or .45 Colt for bears.... ON PURPOSE. However, using one as self defense only... last ditch kind of thing... a .357 is WAY better than a sharp stick. If all you have is a .357, then load it with a heavy, hardcast bullet (or, perhaps the 180gr jacketed silhouette bullet) and go for it. I' d practice with it a BUNCH before going out with it.... make sure I could hit where I was aiming, and do it quickly...
good luck with it.......