Not strictly black powder, but I have shot more than a few pigs with a 12 bore shotgun loaded with ball (as made by the Indian Ordnance Factories who manufacture this from British times) and though this is considered less powerful than a 30-06 round, it does seem to knock pigs down faster when you get to about 25 to 30 yards (maximum) of them.

I am going to buy a black powder ML rifle this year. Just haven't decided whether to buy the Pedersoli or the Traditions U/O. Yes, the latter is not traditional, but it might just be available with a slightly better discount.

Good hunting!