What you have and are comfortable shooting accurately is more than adequate for any black bear in North America. Shot placement is much more important than caliber, and your SST FTX’s will deliver nearly a ton of energy at 100 yds, leaving at least one .50 cal hole and more than likely a .50 cal hole and a softball sized exit hole. Not many CXP2 or CXP3 game that can survive that kind of trauma in parts that matter.No I don't have a muzzle loader. I have shot the Hornady SST sabot slug accurately to 100 yds at the range. Those actual rounds look a lot like some.50 cal muzzle loader rods I have seen.
Bait hunts are usually 25-50 yds at relaxed bear. I shot my last bear with a 265gr FTX over bait and he didn’t go 10 yds. That was with a 444 Marlin hauling about 500 more ft/lbs than yours @ 100 and the Bear didn’t think it was too fragile, and I didn’t recover it. But DeltaHuntr is right about there being a whole bunch of great options out there for slugs. I used to use Hastings out of a TarHunt custom slug gun I had and that was before the Renaissance in slug technology happened 10-15 years ago. Find one you like and go kill a bear with it....no man is ever undergunned with a 12 gauge!