Ted, unless Mr. Moore happens to hold a US FFL no document whether it is a receipt for ownership or a foreign country registration or what ever is going to be sufficient for him to import his own gun. He'll have to use an importer with an FFL.

Your prior posts in this thread have given the impression that an American hunter who travels to Canada to hunt cannot bring his gun back into the USA without the 4457 customs form. I am just trying to correct that mis-information. Certainly the customs form is the easiest method of proving prior ownership in the USA, but not the only way...Geo