Kley-Zion M16/M4 5.56mm & 7.62mm Nickel Boron Complete Bolt Carrier Groups

The treated Nickel Boron finish produces an exceptionally hard surface that’s 40% more wear resistant than chrome plating, with an ultra-low friction coefficient. The surface is harder than the substrate underneath and will not peel, flake, gall, or rub off. Our treated Nickel Boron finish bolt carrier groups have been tested to function reliably without additional lubrication up to 50,000 rounds. Reduced friction also means less heat generated by metal-on-metal contact, so the gun runs cooler and parts last longer. Specifications: Mil-spec Carpenter No. 158 steel Nickel Boron plating HPT Bolt (High Pressure Tested/ Proof) MPI Bolt (Magnetic Particle Inspected) Shot Peened Bolt Chrome Lined Carrier (AUTO) Chrome Lined Gas Key Gas Key Hardened to USGI Specifications Grade 8 Hardened Fasteners Key Staked Per Mil-Spec Tool Steel Extractor Extractor Spring Extractor Insert Mil-Spec Crane O-Ring 100% MADE IN USA