These 5.56 / 300 BLK Bolt Carrier Groups are Melonited, Full-Auto rated, are properly staked, and the bolts are Matched to the barrel. Check your local laws and regulations on ownership guidelines.Our Rosco Melonited Bolt Carrier Groups are designed to meet the modern-day carbine shooters requirements. We have also balanced input from our consumers and military end users in order to bring you the product you need, not just the one we 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 our extensions for extreme accuracy. These BCG's are made to withstand Full-Auto rated fire and unforgiving use from the end user.Carrier Material: 8620 SteelGas Key: 4130 Steel, attached with Grade 8 hardware, properly stakedCam Pin: Hardened 4340Firing Pin: 8740 Steel, Mil-Spec, Center-less ground & Hard Chrome coatedBolt Material: 9310, Properly Heat treated, MPI/HPTExtractor: 4340 SteelEjector: S7 Tool Steel