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.