What are they tracking anyway? You can sell a rifle to anyone can’t you? A private sale of a rifle is still perfectly legal isn’t it?
Can’t you sell the rifle you just bought at Wal-Mart to a crack head in the parking lot if you choose to in most states?
I know a few states have intruded on private long gun sales, but most states have not.
Not if it's prearranged, or they give you the money before hand. Even if not, if they don't get you for a straw man purchase, they may get you for being engaged in the business without a FFL.
Now, if you take it home and shoot it a few times, and sell it a month later, and don't do that more than once or twice year, then you might be OK, but with the BATFErs, you never know.