A buf is not a griz, but what shipmates stationed in alaska carried when fishing were either a 300win or 12ga. In alaska they say you can recognize the tourist - they're wearing a hand gun......
If a double - one tube had #4 buck to fire at the face and blind it - then save the slug for when they could stick the bbl in it's mouth. Some carried a pump/short bbl and loaded buck/slug/buck/slug....
My concern shooting a HARD slug out of a really tight choke would be ripping the end off the bbl. but as long as i hit the buf - who would care.... as you have tubes, put a cyl tube in the bbl you load the slug in.
I have shot a black ba'ar - not a buf - but heavy bone mass with a 3" brennke (recoil is like a 4570 with a heavy load & 500gr slug), it smashed the shoulders and left an exit would you could put your fist in. If you can get them, the BRI sabot would be the shizzle - they were disigned for shooting thru barackades to get gunmen shooting at cops....
Another thing they do in AK, and I think may work well for you, is carry their backup shotgun in a back scabord (like an arrow shoulder quiver) - you could carry a short bbl bakail 45/70 SxS loaded with solids - ubber penitration and no worries of breaking the law.
Sorry for the rambling, still working of first cup of joe...
Gary
