The AR-STONER 6.5 Grendel Bolt Carrier Group is a great option for your next AR-Stoner build. Chambered in the popular 6.5 Grendel caliber, this BCG is machined to strict military standards. State of the art magnetic particle testing ensures the assembly is free of imperfections and will function flawlessly. Featuring a staked gas key, the AR-STONER 6.5 Grendel Bolt Carrier Group is drop-in ready. Note: Upon installation, headspace should be verified by a qualified gunsmith. FeaturesChambered for 6.5 GrendelMachined to Mil-Spec StandardsProperly Staked Gas KeyDrop-In Ready