I have imported several pre 1898 shotguns from England. The seller indicates on the shipping document that it is an 1898, Damascus,(an important word to them) if so. It is sent to the receiving area of the airport and you then take the document to Customs who sometimes realizes that you dont need the ATF Form since it is pre 1898. I have occasionally had to take the ATF book with me to educate them. They stamp the approval and you then go back to the air freight
office and get it. Once they shipped it directly to my gunshop which may work, but maybe not. Most of the time the shipping recipient and Customs are efficient ,but be prepared. One "lady" in customs even told me "if it shoots you need to go through ATF" , but I finally convinced her with the ATF book that it was exempt.