Perhaps you didn't realize that the "lower 48er" was planning to shoot himself rather than be eaten alive. So the real question is "How big a round is needed to penetrate the abnormally thick skull of a numbskull"?
I actually know a guy up here who shot a grizzly with a .38 Special one dark night- it took quite awhile to put him all back together- you can hardly see where they sewed his scalp back, or mended the leg the bear bit clean through...(well, actually, yes, you CAN see the impresive and multiple scars).
MORAL: Don't be too anxious to shoot a big, aggressive animal with a teeny-tiny little gun. Also- "Hunting and alcohol don't mix well"