Well I was under the impression that one from WA could take their firearm to a Oregon FFL and have it transferred to an Oregon resident.
If it were possible and legal then the FFL closest to the bridge would be a boon for us in Oregon wanting to buy from Washington. It would be all most like a ftf.
Washing fella could meet Oregon fella for inspection and negotiation. After that go to FFL do the transfer and Oregon fella pays Washington.
if i've read the laws correctly you can do that with long guns. if it was a handgun you would have to have an ffl from oregon ship to an ffl in washington