Breneke's might be OK, but I'd rather use a hard round ball. I think double shotguns usually regulate more easily with them, maybe not. Mine liked both BP loads, middle and heavy ie: 5 drams and 7 drams plus regualted, of all things, with a smokeless equivelent which kicked less than 1/2 as much. RB's of course.

The round balls will run 460gr. to 575gr. depending on size and compositon - all for a 12 bore.