Frankly I don't get the heavy artillery approach to dealing with bears. My step grand dad took 8 or them with a 30-06. 220 grain bullets. One had a head as big as the front of a jeep.

Also keep in mind, if its a head on encounter, you are lucky to get one shot in. Latest AK is lever action but that's experienced guides that might get more than one shot off and usually its a result of a known shooting (ie. didn't drop the bear the client shot) not sudden encounter.

Hard cast lead slugs. Same for a 30-06 is as good a chance as you will get. Just my opinion. Spent a lot of time in the woods with just a 41 mag. Happy never have had a run in (62 years in AK).