The Rosco Melonited Bolt Carrier Groups are designed to meet the modern-day carbine shooters requirements. They have also balanced input from their consumers and military end users in order to bring you the product you need, not just the one they want to sell you. All Rosco BCG's are to MIL Specification and have a properly staked gas key along with a Melonite coating for extended performance. They also feature a Shot Peened/ MP tested Matched bolt (with upgraded extractor) which is designed to lock up perfectly with their extensions for extreme accuracy. These BCG's are made to withstand Full-Auto rated fire and unforgiving use from the end user.