1. From the Domestic Mail Manual:
g. Antique firearm means any firearm (including those with a matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured in or before 1898, or any replica thereof, if such replica:
1. Is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition.
2. Uses rimfire or conventional centerfire fixed ammunition that is no longer manufactured in the United States and that is not readily available in the ordinary channels of commercial trade.
11.2 Antique Firearms
Antique firearms sent as curios or museum pieces may be accepted for mailing without regard to 11.1.3 through 11.1.6.
The possession of the firearm on post office property was not in violation of 39 CFR 232.1 because the gun itself was there for the official purpose of mailing it.