Oval bore SMOOTHBORES like the one shown at the gunrunners website were enlarged at only the muzzle and had no oval twist in the bore. When loaded with buckshot the horizontal muzzle enlargement was supposed to spread the shot horizontally thus covering a wider area. This was used for close up work as in boarding ships or guarding mail coaches....After looking at the gunrunner site again I see the gun has a TOTAL length of only 41 1/2 inches. That would make the barrel only about 26 inches, very correct for a ships boarding weapon......Ed