Bears are robust and need stout bullets with lots of energy to reliably kill them, right now. I wouldn't consider myself adequately armed for black bear with any .357 load. Mountain lions seem to be more fragile, but I've got one hanging on my wall that soaked up two hits with a Nosler Partition 180 grain at about 2,600 fps, and wasn't down for the count, requiring a coup de grace from my hunting partner's .308. Bayed lions are routinely dispatched with handgun caliber lung shots, but that's fish-in-a-barrel shooting, not defending yourself against an attack. I advise trading up to a .44 Mag or bigger.