I have been told that autos can be bought by milatry, police and one armed men through the internet due to this exception:
Sections 1242 and 1243 of this title shall not apply to -
(1) any common carrier or contract carrier, with respect to any
switchblade knife shipped, transported, or delivered for shipment
in interstate commerce in the ordinary course of business;
(2) the manufacture, sale, transportation, distribution,
possession, or introduction into interstate commerce, of
switchblade knives pursuant to contract with the Armed Forces;
(3) the Armed Forces or any member or employee thereof acting
in the performance of his duty; or
(4) the possession, and transportation upon his person, of any
switchblade knife with a blade three inches or less in length by
any individual who has only one arm.
I live in a state where autos are legal as collector items but not to carry. When they break I take them to the store where the are sold and they send it in by private carrier. They indicated that you cannot ship autos by the USPS.