12 ga with slugs is the preferable answer.
Like a brick at 1500 fps
People up there from natives to military choose differnt forms of bear defense but once your personally aware of or witness a big browns power an speed.
You go big.....some carried a large caliber rifle. I had a 375 H&H that I bought off troop I replaced for that reason alone.
12 gauge turned out to be the best of all. Lightweight an good stopping gun.