Fostech Complete Bolt Carrier Group Black

This is a standard full-auto M16 cut bolt carrier group. It is designed to function with the Echo AR-II and the Echo Sport. Bolt Assembly Bolt: Shot Peened; Magnetic Particle Inspected and Marked Bolt Material: 9310 Alloy Steel Compatibility: .223 / 556 / 300BLK Extractor: Shot Peened Hardened Tool Steel Extractor O-Ring: Viton Mil-Spec Gas Rings (3): Mil-Spec Finish: BLACK NITRIDE Bolt Carrier Material: 8620 Steel Design: Heavy Profile M16 Style (Preferred for most AR-15 Builds) Gas Key Screws: