BCM Upper Receiver - $120
Ballistic Advantage 8.5" 300 BLK out Pistol Length Modern Series 5R Rifling 4150 CrMoV Barrel - $150
Voodoo Innovations Pistol Length Gas Tube LifeCoat - $15
Battle Arms Development Light Weight Low Profile .750 Nitride Gas Block - $35
Noveske KX5 Flash Can Pig - $120
Aero Precision 9" Atlas-ONE Handguard M-Lok FDE - $160

Has ~80 rounds through it to confirm function with supers and subs. Had 0 malfunctions feeding from 6 different types of mags. 
$600 in parts
$450 Buys it.    Text is preferred: four8four-8fourfour-96four1