The FailZero Nickel Boron (NiB) coated (5.56/.223) bolt assembly is compatible with most mil spec AR15, M16, M4 bolt carriers. The special EXO Nickel Boron coating provides a permanent dry lubricity
*Does NOT include Bolt Carrier*
Nickel Boron treated parts include:
*Does NOT include Bolt Carrier*
Nickel Boron treated parts include:
- EXO Coated Bolt - Case Hardened, Shot Peened and MPI (Magnetic Particle Inspected)
- EXO Coated Extractor (fully assembled)
- All other components are Mil-Spec
