Unless the ATF form has changed, the gun can come directly to the person who bought it. FFL holder required to sign, but it's up to the individual receiving it to take it to the FFL holder and complete the paperwork. Mine came from the UK, direct to my post office. Postmistress acted for Customs--which she advised me she'd done previously, although never on a firearm. Collected duty and customs fee. I walked out with the gun, took care of the 4473 with the FFL afterwards. (Nobody but govt can act for the govt, so neither FFL nor licensed importer could collect duty, fees, etc..) It's my understanding that importers have to stamp; FFL's making occasional imports do not.
I can't comment about accessing customs offices when receiving a gun, but I've accessed them to fill out the required form when I've taken a gun overseas with me. Both at the Des Moines airport and at Ohare.
But, as I said, lots of reasons to use a licensed importer in case something goes astray. I've heard from people who had problems I did not have.
