the barrel is chrome lined no info available on the bolt so please contact bushmaster at Phone: 1-800-883-6229 or by email: bushmaster.com/contact

Josh, The upper receiver is forged from 7075 T6 aircraft aluminum hard anodized finish to a mil-spec dark gray, The barrel is chrome lined. All other exposed steel components are manganese phosphate coated. There are only three coating choices for AR BCG coatings; manganese phosphate, nitride, and nickel boron. Nitride is probably the most durable, nickel boron is the "slickest" in terms of lubricity, and manganese is a lower cost alternative to nitride. Most likely they are using manganese coating on the BCG.

Josh, this upper includes a 16" heavy-profile, match grade, chrome-lined barrel. Bolt is not mentioned so Bushmaster would need to verify if one is included at Phone: 1-800-883-6229 or by email inquiry here : bushmaster.com/contact