Interstate long gun transaction into NYS
I am not a lawyer, but I don't want you to hang here waiting for answers forever. First, I'm pretty sure that FTF (face to face) transfers of firearms (including long guns) can only take place between residents of the same state, per federal law. I'm sure this is an easy one to verify or disprove; just check the ATF website (FAQs to start) or perhaps the NYSRPA or NRA-ILA websites. (I'd do it for you, but I'm a bit pressed for time right now.)
As for NY-specific rules, NYS has a two-feature AWB modeled on the 1994 federal AWB which did not sunset (like the Federal ban did), so the AR would have to be ban-compliant (or "pre-ban" per NYS law). Also, all magazines over 10 rounds would have to be pre-ban as well (note that this is regardless of the "ban status" of the rifle itself). Beyond that, several locales within NY have their own AWBs of various stripes (e.g., NYC). I only know the NYC AWB, which is a ban on possession and disposition within NYC that would not affect you as the seller (unless you brought the AR into NYC to complete a sale, which would be a direct violation).
As your sale will have to go through an FFL (either in your state or NY), you'll be helped insofar as the FFL is required to know the laws of both states and effect the transfer in compliance with such state laws. However, I would recommend that you spend some time to research the relevant statutes and rules yourself. You don't want to inadvertently break a law or rule just for the sake of a sale.
