If I was in griz country I would more than likely have a shotgun loaded with some realy hot slugs, and buck shot. Backed up with an Ruger Alaskan in .454 Cassul.
For the sake of awnesering I would choose either, though I would make sure they were either loaded with hard cast bullets, or some form of non expanding bullets to get maximum penetration. For most black bears either would do the job.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.