Never content to settle on the mil-spec, we manufactured enhancements directly into the receiver: The receiver is trued (blueprinted) by Faxon at the factory We hone the inside bore to smooth out the action of the bolt carrier group. Hollow-out the shell deflector to reduce weight and look great Manually engraved T-marks on the upper. Will stay visible after any coating Hold tighter tolerance on the lugs for a better fit?Specifications: Material: 7075-T6 Forged Aluminum Finish: Type III Hard Coat Anodizing Caliber Compatibility: All intermediate cartridges. .458 and large bore rounds may not function in the intermediate upper.? Weight: .43 Lbs (6.88 Ounces)