Do NOT try that, Storms! I didn't even try it with a gun I'd acquired legally while working abroad as a diplomat! If you take a gun overseas with you, it has to be declared to US Customs (not to mention TSA) on your way out of the country. You can only bring back in what you declared on your way out. If you didn't declare anything on the way out, you can't bring anything back in.
Eightbore, no steps were skipped in my case. The British dealer, familiar with sending guns to the States, shipped it via Datapost. It cleared Customs, exactly as it was supposed to. Under Customs regs, apparently a postmaster can act on behalf of Customs and collect their duty, because right on my completed ATF Form 6, there's a note from Customs to my PO, telling them how much to collect. I was not aware of any value limit, and David could be right on that score. Maybe I would have had to go to the nearest Customs office had the gun been more expensive.
John, I was not aware ATF had gotten more strict on the import rules. Every now and then, you run into a bureaucrat who says "no, you can't do that" even when the written rules say otherwise. Back when I flew to my post in Morocco (1971), you could still take a gun as carry-on and hand it to the flight crew; it rode in the cockpit, with the pilot. I had done that from DC to NY, then had a PanAm ticket agent tell me it was against the rules--that in spite of my diplomatic passport. Fortunately, the crew came along about that time, and the pilot settled the matter by overruling the ticket agent. But I did have some interesting experiences clearing customs and immigration on the Casablanca end, carrying a gun two months after there'd been a coup attempt in which the army had tried to kill the king.
