I just got off the phone with the guy who built the barrel! Good News! The barrel is constructed of either 1018, or 1020 steel. The trunnions are pressed in, and tack welded. The guy is a machinist and built it in 1985. The no wad, no ball and 50gr powder info on top is strictly put their for liability reasons. This cannon is one of a kind, it is the only one of this type he built. He has since moved on to large artillery pieces. This cannon is capable of full charges up to the muzzle! A reccomended charge for this is a 1" square load of BP. This guy is very experienced, and has been building and shooting for over 30years!
It is about time to drill the vent