Avlrc, my .P.GONTER. has those little circles as a decoration across the flats at the breech, with a bellflower & crossed arrows somewhat further on. These marked, with the early trade gun style trigger, suggests it was made for the Indian trade. It is a .56 cal 1/2 round "Kentucky fowler", i.e. heavy wall barrel to handle ball as well as shot. Never had it apart to see any Roman numerals.