The Rosco Manufacturing Rosco 556NATO/300BLK BCG Phos Blk is a dedicated bolt carrier group built for AR-15 platforms chambered in 5.56 NATO and 300 Blackout. Finished in a phosphate coating with chrome-lined gas key and bolt channel, this BCG is engineered to deliver dependable cycling and long-term durability under hard use. Each bolt is carefully matched to the barrel and tested to meet military specifications for reliability.

This bolt carrier group is well suited for range use, training, and general-purpose rifle builds where consistent performance is a priority. Its full-auto rated construction and upgraded extractor components support smooth operation across a wide variety of ammunition. Shooters looking to upgrade or complete an AR-15 upper will appreciate the attention to detail Rosco Manufacturing brings to this Microbest-produced BCG.

Key Features:

• Manufacturer: Rosco Manufacturing
• Model: 556NATO/300BLK BCG Phos Blk
• Product Type: Bolt Carrier Group
• Caliber Compatibility: 5.56 NATO / 300 Blackout
• Finish: Phosphate with chrome-lined gas key and bolt channel
• Bolt: C158, phosphate coated, MPI/HPT tested
• Carrier Material: 8620 steel
• Gas Key: 4130 steel, properly staked
• Extractor: 4140 steel, heat treated, shot peened with upgraded Sprinco kit
• Firing Pin: 8740 steel, hard chrome plated