The original prototype, which I built and still have pictures of, was indeed built based on the O'connor gun made by Richard Wilson. We also studied the Museum of the Great Plains gun, which has the earlier "flat serpent" side plate as does NSW's EE gun. The Great Plains gun has the smaller trigger guard, and is made of brass. All were variations of what Hamilton and Hanson catagorize as the type "G" pattern. Even common trade guns, while following a pattern of guidelines differed from maker to maker. The differences, although subtle, are distinctive enough to identify the manufacturer with out signatures. The same differences hold true for guns manufacured in Britain, North America and Belgium. For real fun, look in Hamilton's book at the "Chiefs Grade Indian gun" that was in Curly's collection. I've held this gun in my hands. speculation is that it was made in India and was their interpretation of an "indian" gun, decorated in East Indian fashion. As long as a trade gun fits into the respective "pattern", there is, to quote Curly " no incorrect trade gun. So have fun with your trade gun, whichever version or variation you have.