In a 12 bore smooth double, I've used 115gr. 2F, 150gr. 2F and 191gr. 2F, all with a .690RB held centred in the cup of a plastic wad's gas check, cup end up and sitting on the over powder wad.
The 150gr. and 191gr. loads match loads listed in Greener's book for BP 12 bore ammo - except my ball size probably differs. These loads can be used with any ball size, btw as long as it isn't oversizwe for the gun.
I suggest the 191gr. load, 7 drams, isn't for 7 pound guns. Kicks a bit for those and is hard on stocks.