Not long range but I have the chance to hunt black bear in PA and the shot would be under 100 yards more likely 25-50 yards. Can't use a long range rig so it leaves me with a 32 Win Special with a 1-5x or a 12 gauge slug gun. Not a big deal if it's a 250 lb bear but by chance a large PA bear shows up I want to hit it hard enough.
"Fast is fine accurate is final"
If your 12 gauge is accurate and you have the right slugs it is very deadly. Just be careful with slugs to get something designed for penetration not a deer load that expands too fast. I tried 5 types recently but can't find the info right now. I think this was the one I liked best:
Either weapon will be fine. Black bears do not take that much killing to put them down. At the ranges you described the thirty-two would be great. I live in Idaho and have killed 6 bears. One was with a 6mm. He went 45 yards. Good shot placement is the key. I carry a 7mm mag now but it is just because of all the dang grizzly's here. My rifle of choice would be a 25-06.
Good luck, Kirk
Got my bear this spring with a 45-70, 405gr rem soft point (custom load,about 1700fps). The distance was 75 feet!! Was at upper position thant the bear, take a neck-spine shot at the shoulder junction.... Blown out about 3 1/2 inch of the spine!!!!!!!
If not long range shot both of your choice will be good. Just practice and our bear will be down fast.
Chance are that your bear is alwredy down? How dos your hunt wen?
I use a 12 gauge with 3" Winchester partition gold. At that range I have broken both front shoulders on 300+lb bear with exit and creates a tremendous amount of shock compared to any other shotgun shell I have ever heard of.