NIB AR/M16 5.56/.223/.300 BLACKOUT caliber complete Black Nitrided Bolt Carrier Groups.  Shot peened, MPI (Magnetic Particle Inspected), 9310 Tool Steel Bolt; 8620 M16 carrier, Properly staked 4140 Machined Gas Key fastened with Hardened Grade 8 Fasteners. Extractor includes crane o-ring.  Manufactured for AIM Surplus.