Microboomer,
That isn't necessarily so, I've seen real cast iron guns that show parting lines, but as a general rule the foundries did work off the lines (although they weren't trying to win any beauty contests with the finishes on iron cannon).
ironglow,
You could have the same type of four truck carriage, and it would be called a naval carriage if it was on a ship's gun deck, or a garrison carriage if it was positioned on a seacoast fortification. The wheels on a garrison carriage were often made of iron, while a ship's carriage had wooden trucks.