FailZero Bolt Carrier Group with Semi Automatic Hammer nickel fits M16/4

Description This Bolt Carrier Group (BCG) comes fully assembled and ready to drop into most mil spec M16 M4 or AR15 upper receivers. All critical parts are coated with EXO Nickel Boron technology that provides permanent dry lubricity extreme durability and increases both wear and corrosion resistance. Nickel Boron treated parts include: Bolt & Extractor (5.56/.223 compatible) Bolt Carrier Semi-Auto Hammer (single stage) Extractor Cam Pin Carrier Key Firing Pin