I did not intend to appear as if trolling when I posted earlier above about the S&W 460. After reviewing my post this morning I can see where it could be interpreted as such.
I have a close friend that is an astute gun collector and he chose to purchase the S&W 460 versus any one of the other extreme magnum revolvers based on both the ballistics and the gun’s relative size to weight ratio. The 5 inch barrel is 11.25" OAL and 62.5 oz. He is also a gun rep and salesman for CDNN online.
And if I may add my humble responses below to the previous recommendations:
It may be destructive to people and to people wearing body armor; however it would have a miniscule effect against the muscle and bone mass of a bear. The 5.56mm bullet weight is only 23 to 28 grains as compared to 250+ grain weight of magnum calibers.
I would recommend at least a .44 Mag (especially if you can borrow one rather than purchase one for what appears to be a one-time need), and I would argue against the use of a shotgun for a hiking endeavor. A revolver in a belt holster is way quicker to deploy than a rifle or shotgun, not to mention less threatening than a long gun would be to other hikers.
When I hike I like to enjoy nature with as little intrusion into the environment as possible, as I am sure any hikers that I may meet along the way would not appreciate hearing what would seem to be a disturbed person if following such advice. There again in my honest opinion if you need to make noise to thwart a threatening bear encounter, a magnum revolver is the only sensible means of providing the stopping power and incidental noise.
I would argue that if a S&W .460 or a .500 S&W Magnum will not stop a charging black bear then neither will a shotgun with solid slugs.
[Federal® Truball® 12 ga.- 2 3/4" - 1 oz. Slugs - Velocity: 1,600 ft/s - Muzzle Energy: 2,485 ft-lbs]
.460 S&W Magnum - Wikipedia, the free encyclopedia
Whatever you choose it goes without saying the need to determine the applicable gun "carry" laws for your planned hiking route.