W.W. Greener lists 3 loads for the 12 bore - I assume for the 2 1/2" to 2 3/4" hulls. The 7 dram load fits well in the 2 3/4" with a roll crimp.

116gr., 150gr. and 191gr. - 4 1/4 drams, 5 1/2 drams and 7 drams.

The 3" hull used up to 9 drams = 245gr. and weighed in the 12 to 13 pound range, I think. Peter in Denmark has just such a double gun.