Description
The Aero Precision PRO Series 5.56 Bolt Carrier Group is built from the ground up to meet the demands of the most extreme conditions. Each component and manufacturing process of the PRO Series 5.56 Bolt Carrier Group was deliberately chosen to increase the reliable service life of the bolt carrier group and its components. Firing Pin: Ground from 8640 Steel Nitride Finish Gas Key: Machined from hardened 4140 steel Torqued to spec with grade 8 hex fasteners Properly staked to Mil-Spec Nitride Finish Cam Pin: Machined from 4140 steel Precision ground after heat treatment Engraved Indexing mark Nitride Finish Ejector: Machined from S7 tool steel Extractor: Machined from 4140 Steel Heat Treated Shot peened Phosphate Finish Bolt: Machined from 9310 steel Critical Surfaces precision ground for optimal gas efficiency and reliability Shot Peened MPI Tested Proper Heat Treatment ensured via proprietary flash-nitriding Carrier: Machined from 8620 Steel M16 Cut Carrier Nitride Finish