Product Description Sons of Liberty Gun Works (SOLGW) considers the bolt carrier group (BCG) the heart of the AR-15 platform. Just as the gas port serves as the lungs, the BCG drives the entire cycle of operations - locking, unlocking, extracting, and ejecting. The SOLGW OCKS BCG is built around a Carpenter 158 steel bolt and a durable phosphate (Parkerized) finish, engineered to withstand the most demanding conditions. The standout OCKS (Optimized Carrier Key Screws) upgrade ensures a rock-solid, long-lasting gas key attachment secured with Grade 8 fasteners that are properly staked. Every bolt is full-auto test fired at assembly, giving you confidence in its reliability from day one. Compatible with multiple popular calibers and featuring a full-auto profile carrier, this BCG is the premium choice for duty use, competition, or recreational shooting on the AR-15 platform. Product Highlights Compatible with 5.56 NATO, .223 Remington, .300 Blackout, 6MM MAX, and .350 Legend for broad multi-caliber versatility Full-Auto Profile Carrier with every bolt full-auto test fired at assembly for proven, out-of-the-box reliability OCKS (Optimized Carrier Key Screws) upgrade features Grade 8 fasteners with proper staking for a secure, lasting gas key connection Carpenter 158 steel bolt with a phosphate (Parkerized) finish delivers superior durability and corrosion resistance Premium mil-spec AR-15 component engineered by Sons of Liberty Gun Works for consistent feeding, extraction, and ejection Specs Brand: Sons of Liberty Gun Works MPN: SOLGW-BCG556-OCKS UPC: 657628674153 Compatible Calibers: 5.56 NATO, .223 Remington, .300 Blackout, 6MM MAX, .350 Legend Carrier Profile: Full-Auto Bolt Material: Carpenter 158 Steel Finish: Phosphate (Parkerized) Color: Black Key Screw Upgrade: OCKS (Optimized Carrier Key Screws) with Grade 8 Fasteners, Properly Staked Testing: Full-Auto Test Fired at Assembly Platform: AR-15 Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product&';s manufacturer.