Product DescriptionThe Geissele Stress Proof Bolt Assembly is engineered for shooters who demand exceptional reliability, durability, and long service life from their AR-15 or M4 platform. Built around a forged Stressproof bolt made from Carpenter 158+ steel, this assembly is designed to deliver substantially greater fatigue resistance than standard mil-spec bolts. Each bolt is rigorously high-pressure tested, magnetic-particle inspected, and shot-peened for confidence under hard use. The included extractor is paired with Geissele&';s Nanoweapon coating, which helps reduce friction while enhancing wear and corrosion resistance for smooth, consistent function.Product Highlights Forged Carpenter 158+ Stressproof bolt designed for enhanced strength and extended service life Includes extractor and related bolt components for a ready-to-install bolt assembly Nanoweapon-coated bolt and extractor help reduce friction and improve corrosion and wear resistance High-pressure tested, magnetic-particle inspected, and shot-peened for dependable performance Compatible with AR-15 and M4 platforms chambered in .223 Remington, .223 Wylde, 5.56 NATO, and .300 Blackout Specs Product Type: Bolt Assembly Brand: Geissele Automatics Manufacturer Part Number: 05-2991 UPC: 810081134972 Bolt Material: Carpenter 158+ forged steel Extractor Material: 300M stainless steel Finish/Coating: Nanoweapon coating Testing: High-pressure tested Inspection: Magnetic-particle inspected Additional Quality Control: Shot-peened Includes: Bolt, extractor, extractor spring, O-ring insert, ejector, ejector spring, and pin Compatibility: AR-15 / M4 platforms chambered in .223 Remington, .223 Wylde, 5.56 NATO, and .300 Blackout Weight: Approximately 1.54 oz assembled 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.