I have a 1928 Ishapore converted SMLE mkIII .410 shotgun that I would like to convert to a .45apc carbine. Because it was imported and registered as a shotgun, do you think I will have to receive permission from the BATF or have to re-register it if I convert it? I browsed the BATF's website and FAQs, but I didn't see anything covering this topic.