Rosco Manufacturing 5.56 NATO/300 BLK BCG Melonite Black – AR-15 Bolt Carrier Group

The Rosco Manufacturing 5.56 NATO/300 BLK Bolt Carrier Group is a mil-spec replacement or upgrade BCG designed for reliable cycling in AR-15 platforms chambered in 5.56 NATO or 300 Blackout. This BCG handles the core functions of extraction, ejection, and chambering—critical to consistent performance whether you're running supersonic 5.56 or subsonic 300 BLK loads. Shooters replace factory BCGs to improve reliability, reduce fouling buildup, or maintain a spare for training and competition use.

Constructed from 8620 steel with a Melonite finish, this carrier group offers corrosion resistance and reduced friction for smoother operation and easier cleaning. The Melonite treatment penetrates the steel rather than coating the surface, providing long-term durability under high round counts. This is a drop-in part compatible with mil-spec AR-15 upper receivers—no gunsmithing required for installation.

• Part Type: Bolt Carrier Group
• Compatible Firearms: AR-15 chambered in 5.56 NATO, .223 Remington, 300 Blackout
• Material: 8620 Steel
• Finish: Melonite (Black)
• Installation: Drop-In
• Includes: Bolt Carrier Group Assembly