This Bushmaster® Bolt Carrier Group will make a great addition to your favorite firearm or new build. The bolt is made from Carpenter 158 Steel and Magnetic Particle Inspected for absolute durability. The carrier group is finished with Salt Bath Nitride, which enhances the wear and corrosion resistance of this crucial part. Included on the carrier is the official Bushmaster® logo for recognition. Use the BCG with calibers including 5.56 NATO, .223 REM, 300BLK, 350 Legend, and more. Grab your Bushmaster® Bolt Carrier Group 5.56/300BLK C158 Steel today and experience PROVEN® Bushmaster® quality. Features & SpecificationsBolt Material: Carpenter 158Bolt Carrier Group Finish: Salt Bath NitrideBolt Testing: MPI Tested (Magnetic Particle Inspection)Calibers: 5.56 NATO/ .223 REM/ 350LGND/300BLKProudly made in the: U.S.A.