These are the original parts I had to replace in my rifle in order to make it legal.  The shiny rod at the top is the gas piston, the cylindrical object below it is the original flash hider, the object to the far right is the front half of the upper receiver, the bottom part in the center is the trigger, the object directly above the trigger is the sear, the piece to the left of the sear is the hammer, and the large black plastic piece is the pistol grip.