Steve, not to argue but...... if you are selling one of your guns, you absolutely can ship it to the FFL holder in another state. Look at the ATF site I posted above and look under section B1 of the FAQ's.
B. UNLICENSED PERSONS
(B1) To whom may an unlicensed person transfer firearms under the GCA? [Back]
A person may sell a firearm to an unlicensed resident of his State, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may loan or rent a firearm to a resident of any State for temporary use for lawful sporting purposes, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may sell or transfer a firearm to a licensee in any State. However, a firearm other than a curio or relic may not be transferred interstate to a licensed collector.
[18 U.S.C. 922(a)(3) and (5), 922(d), 27 CFR 478.29 and 478.30]
I do think that I am right here. We will see...
