Most BCG's on the market today do not meet Mil-Spec standards one way or another; but Q's not only exceeds the specifications, but the design and size of the Front end makes it easier to control the manufacturing of critical features. Smart people stuff. The Two Piece BCG is designed to be manufactured on modern equipment using modern materials. Their BCG consists of 2 sections; The Front-End and The Rear-End The front end is made up of Maraging Stainless Steel dressed in black with a Nitride Coating, and is SCAR-Cut to help prevent bolt bounce. Standard with: Mil-Spec Gas Key and Staking, Mil-Spec Bolt, Mil-Spec Cam Pin, Mil-Spec Firing Pin. The Rear-End is naked Stainless Steel, heat treated of course and yes, the overall length is Mil-Spec. The Rear-End holds the firing pin, doing away with pesky firing pin retaining pins. No more broken pins. You're welcome. The Carrier is retained with a single Pin allowing for easy field stripping.