For a bear gun I have thought about afew of guns. A marlin .444 < i need a lever gun
> a 12 ga with a rifled slug barrel, and maybe even a .260 remington though that may be a little on the light side. I know I will never shoot over 50 to 75 yards at the most in the areas I will be hunting in.
For the distances you will be shooting the guns you already have would work great, but if you are wanting a big gun just for bears the Marlin .450 works great. I have one we use for hogs and it really leaves a big hole.