Receiver comes complete with forward assist and trapdoor.This was removed from a upper assy. that I bought from M&A parts. That is not rust on the trap door it is some kind of stain that has been there since it was new and dose not show up as much as the camera shows it. This upper has no more than 500 rounds shot thru it. $90.00 Price includeds shipping in con. u.s. I'll take a M.O. or paypal.