There is so much confusion and ambiguity regarding "gun parts" that I always pack my extra scope in the gun case with the rifle. Binos and spotters go in the carry-on.
And.....I always carry copies of the TSA and airline regs with me. That said, it always boils down to the mood of the authority figure at the airport. You can argue for hours if you want to. You might even prevail.
Then guess whose gun case or checked bag WON'T arrive at its destination?
