I am not sure how much blackpowder the English considered maximum in a 12 bore 3" case. Certainly 9 drams would be getting there. Isn,t the Tolley an original BP gun? You have to start to wonder what load the designer of this gun had in mind. A 7 dram 12 bore conical gun weighs about 13lbs. An 8 dram 10 bore weighs in at about 14lbs with a 900gr bullet.