I'm trying to put together my upper and I'm missing the barrel nut. I've attached two pictures. It's the silver nut in the picture that's threaded into the receiver and it's the nut with the flats in the other picture. I've reached out to seekins and I can't get through on the phone. Their customer service already sent me the incorrect part... So I figured I'd try my hand here while I try and get things fixed on their end.
