Guntec USA AR 9mm Bolt Carrier Group BCG Mil-Spec Nitride. Just Released Compatible With Glock & Colt Style Lower Receivers. Specifications for Guntec USA AR 9mm Mil-Spec Nitride Bolt Carrier Group (BCG): Manufacturer: Guntec USA Color: Black Finish: QPQ Salt Bath Nitride Fabric/Material: Mil-Spec 8620 Steel Carrier Material: 8620 Steel Bolt Material: 9310 Steel Caliber: 9mm Luger Gun Make: AR Platform Gun Model: AR-9 Weight: 14.9 oz Condition: New Features: Dust Cover Compatible Fully Heat Treated 1 Year Warranty Package Contents: Guntec USA AR 9mm Mil-Spec Nitride Bolt Carrier Group What firearm models does the manufacturer say Guntec USA AR 9mm Mil-Spec Nitride Bolt Carrier Group (BCG) is compatible with? The manufacturer says that Guntec USA AR 9mm Mil-Spec Nitride Bolt Carrier Group (BCG) is compatible with AR-9GUNTEC USA GT-BCG-9: AR 9mm Cal Mil-Spec Bolt Carrier Group Nitride