You want to be careful with ITAR, and and the US Dept od Commerce,
You might want to check with your IOI contact at the ATF George even thou its an antique here.http://www.borderview.com/services/for-individuals/pre-1899-export-exemption/
United States law (specifically the “ITAR” – International Traffic in Arms Regulations”) allows for the export without an export license of firearms (rifles and pistols) that were manufactured before January of 1899, or replicas of such firearms.
This guide provides some details about the so-called “Pre-1899 Exemption.” Here are the basics: Does not apply to Shotguns: shotgun exports are regulated by the U.S. Department of Commerce rather than the U.S. Department of State, and there is not an equivalent exemption for shotguns
You could also try these guys here,note the "not for resale" parthttp://www.usaigroup.com/export-import-compliance/
ITAR currently authorizes Customs to permit the following exports of defense equipment without a license: (1) non-automatic firearms manufactured before 1898 (collectibles and antiques) and replicas, (2) minor components for certain firearms that do not exceed $100 wholesale per transaction and (3) temporary exports of up to three non-automatic firearms and up to 1,000 cartridges per U.S. citizen or resident alien if the firearms are intended exclusively for personal use (hunting or self-protection), are not for resale
, and are shipped as baggage.