Bolt is made of Mil-spec Carpenter 158 steel, Shot peened, High pressure tested and Mag Particle Inspected. Gas key is machined out of bar stock, chrome lined phosphate coated, and secured with grade 8 fasteners and staked per mil-spec. Bolt carrier is phosphate outside and chrome lined inside. For packaging considerations, BCG will be packed dry. As a result, it will have a grey, dusty appearance that will turn black with the application of CLP or other preferred lubricant.