PSA AR-15 Bolt Carrier Group 5.56 Full-Auto Nitride MPI - 516446953

.223/5.56 Bolt Carrier Group - Black NitrideThe .223/5.56 Black Nitride Bolt Carrier Group was designed with strength in mind. Starting with a 9310 Steel Bolt, which is aircraft-grade material, this bolt has high core strength, fatigue strength, and hardenability. 9310 steel, when appropriately treated, is about 7% better than Carpenter 158 steel, so you know that you will have a dependable BCG when you drop this into your rifle.This BCG (Bolt Carrier Group) has been Nitrided to provide a long-lasting experience and a significant upgrade to your AR-15. These BCGs have also been Magnetic Particle Inspected and have been made to Mil-Spec Standards. It also has Mil-Spec 8740 Steel hard-chromed Firing Pins, Mil-Spec Gas Keys with Grade-8 screws staked and sealed with Permatex No. 3, and shot-peened, case-hardened D2 tool steel extractors.NOTE: The Salt Black Nitride BCG offers a dark, subdued finish that doesn't change the Bolt Carrier's specs, but it still makes the outside harder. This treatment increases the part's longevity, makes it extremely wear-resistant and durable, and protects it from corrosion.Specifications Gas system: Direct Impingement Caliber: 5.56x45mm NATO/.223 Rem, .300 Blackout Finish: Salt Black Nitride Bolt: 9310 Alloy Steel (High Hardness) Carrier: 8620 Aircraft Grade Steel Extractor: Shot Peened and Case Hardened D2 Tool Steel Firing Pin: Mil-spec 8740 steel with hard chrome finish Gas Key: Mil-Spec w/ properly staked Grade-8 screws & Permatex No. 3 sealed Cam Pin: 8620 Steel w/ Black Nitride Finish Quality Control: MPI Inspected for QC