To the best of my knowledge Fowlers were not traditionally used with anything but shot. Bird shot, swan shot, maybe buck shot. The barrels were thin for easy, quick handling. Not for round balls. But again, I’m no authority on the subject. But I have heard and read Jim state that he hoped folks would stay with shot. But he still has to make the barrels heavier than originals because people are bound to put RBs in them. Not sure about his barrel shape, we’ll know pretty soon. If you dovetail a round barrel it better be a thick walled one. Just not traditionally done. Fowlers and Trade Guns are both smoothbores but different animals.