Battle Arms Development Enhanced Bolt Carrier Group - Full Auto M16 Bolt Carrier, 9310 Bolt, Black Nitride Finished, Laser Engraved BAD Inc. Logo. Complete Bolt Carrier Group.  The new bolt carrier geometry was designed to reduce carrier tilt and the key bearing surfaces are reloacted to increase reliability.  Having fewer points of contact and an ultra-hard & bricious black nitride surface layer reduce friction and improves funciton.  

• Bolt Carrier: 8620 Steel Case Hardened, Machined from Billet, Laser Engraved Logo
• Firing Pin:  8740 Steel, Centerless Ground, Hard Chromed
• Gas Key:  4130 Steel with Grade 8 Screws, Properly Staked, Machiend from Billet
• Cam Pin:  4340 Hardened Steel
• Finish:  Black Nitride finished with an ultra-hard, corrosion resistant top surface layer for wear resistance and minimal need for lubricants.  Most importantly, Black Nitride is a surface conversion process with little to no surface build-up (1-2 microns) keeping critical tolerances precise, unlike NiB, Hard Chrome, etc. which are additive and will alter the dimensions of the steel.
• Bolt:  9310 Steel, Cased Hardened, Shot Peened, Mil-Spec Dimensions, CNC Ground After Heat Treat, Black Nitride Finished
• Extractor:  4340 Steel, Manganese Phosphate Finished for Positive Grip (no slippery finish)