OK, 18USC Section 921 defines antique firearm:
(16) The term "antique firearm" means -
(A) any firearm (including any firearm with a matchlock,
flintlock, percussion cap, or similar type of ignition system)
manufactured in or before 1898; or
(B) any replica of any firearm described in subparagraph (A) if
such replica -
(i) is not designed or redesigned for using rimfire or
conventional centerfire fixed ammunition, or
(ii) uses rimfire or conventional centerfire fixed ammunition
which is no longer manufactured in the United States and which
is not readily available in the ordinary channels of commercial
trade; or
(C) any muzzle loading rifle, muzzle loading shotgun, or muzzle
loading pistol, which is designed to use black powder, or a black
powder substitute, and which cannot use fixed ammunition.
Now, to find out if an "antique firearm" reqires FFL shipping. I kinda remember not....
Edit: Found the rest:
'Antique' firearms need not be shipped to a licensed dealer. These can be shipped directly to the buyer. An antique firearm is a firearm built in or before 1898, or a replica thereof.