A B Arms A*B Pro 5.56mm Bolt Carrier Group - Complete Nickel Boron Assembly

Bolt

9310 Steel
Heat treated per Mil-Spec Requirements
Shot Peened per Mil-Spec Requirements
MPI Tested Material
Nickel Boron Coated
Bolt Carrier

8620 Steel
Nickel Boron Coated
Nickel Boron Coated Bore
M-16 Style with more mass for better functioning in semi or full auto rifles
Gas Key

4130 Steel
Nickel Boron Coated per Mil-Spec Requirements
Gas Key Screws – 4140 Steel Properly Staked per Mil-Spec Requirements
Cam Pin

4340 Steel
Heat Treated per Mil-Spec Requirements
Nickel Boron Coated per Mil-Spec Requirements
Extractor

Aircraft Quality E4140 Steel
Heat Treated per Mil-Spec Requirements
Shot Peened per Mil-Spec Requirements
Nickel Boron Coated per Mil-Spec Requirements
Firing Pin

420 Steel
Passivated