Spikes STU5435R2S Complete Upper 5.56x45mm NATO 16" Black Phosphate/Midlength Barrel, 7075-T6 Aluminum Black Receiver, 12" SAR3 Free-Floating Handguard for AR-15 $788.40
Aero Precision APAR700201C M4E1 Threaded Receiver 5.56x45mm NATO 7075-T6 Aluminum Black Anodized Receiver for AR-15 $134.99
Aero Precision APAR308505C Receiver 308 Win 7075-T6 Aluminum Flat Dark Earth Cerakote Receiver for M5 Platform $189.99