A 12 ga is excellent with either slugs or as mentioned "hard" buck shot. A few companies make shells specifically for "bear attacks".
I will point out one thing. Even with a sling, you will not have your shotgun easily accessable 24/7. A good large caliber revolver (.41 mag, .44 mag or .45 colt) on your person is always there. No it's not as "powerful" as a shotgun, but much more useable than the shotgun several feet away.
I will point out one thing. Even with a sling, you will not have your shotgun easily accessable 24/7. A good large caliber revolver (.41 mag, .44 mag or .45 colt) on your person is always there. No it's not as "powerful" as a shotgun, but much more useable than the shotgun several feet away.