I am helping someone do a firearm trade in WA. They have found someone to trade pistols with and to be in compliance will meet at an FFL to do the transfer. Being Washington, how is the Sales tax done? If he was buying a pistol, then you have a cash value upon which to base the tax. But for a trade? I know when I sold this guy a gun, he had to pay sales tax even though I am in Oregon, as the transaction across state lines required an FFL who was located in his state. This is Private Party to Private Party, not across state lines. The dealer is just to complete the BGC. TIA If this is already answered somewhere, just point me at that. If not, maybe it could be added to a FAQ.