6.5 Grendel Type 2 bolt face – Black Nitride Bolt Carrier Group. – Technical Specs – Type 2 6.5 Grendel bolt face. – True Mil-Spec Bolt Carrier Group – Material: Case Hardened 8620 Steel – Finish: Black Nitride. This advanced low friction coating minimizes the need for lubricants. – Gas Key: 4130 Steel attached with Grade 8 hardware and properly staked into a milled “valley” to ensure proper positioning. – Cam Pin: Hardened 4340 cam pin – Firing Pin: Mil Spec firing pin made of 8740 steel center-less ground and Hard Chrome coated – Bolt Assembly: The Bolt is “true” Mil Spec dimension and external surfaces are CNC ground after heat treat for a precision fit. – Bolt Material: Case Hardened 9310 Steel. – Finish: All Bolt components Shot Peened and Manganese Phosphate or Black Nitride – Extractor: 4340 Steel Manganese Phosphate coated – Mil Spec Extractor Spring & O-Ring Combination – MPI: Magnetic Particle Inspected – HPT: High Pressure Test – Made in USA