Geissele Stressproof AR-15 Bolt Assembly - SKU: 05-2991 - UPC: 815671015693
Product Description
The Geissele Stressproof AR-15 Bolt Assembly (05-2991) is a duty-grade replacement bolt engineered to eliminate the primary mechanical failure points found in standard mil-spec AR-15 bolts. Developed by Geissele Automatics for high-round-count operational schedules, suppressor use, and short-barreled rifle (SBR) staging, this 5.56 NATO bolt is forged from proprietary Carpenter 158+ alloy steel—a cleaner, higher-purity steel matrix that provides up to five times the fatigue life of standard Carpenter 158 steel.
To prevent lug shearing under violent backpressure and rapid firing cycles, Geissele redesigned the bolt geometry by adding extra material to the critical bolt lug radii and stress concentration points surrounding the cam pin hole. The assembly features a heavy-duty extractor forged from a proprietary alloy, complete with a dual-spring architecture that maintains positive rim engagement and reliable extraction without relying on easily degraded rubber O-rings.
Individual High-Pressure Tested (HPT) and Magnetic Particle Inspected (MPI), the 05-2991 bolt is finished in a slick, durable manganese phosphate coating that retains lubrication and resists environmental corrosion. It installs as a direct drop-in upgrade for all standard mil-spec AR-15 bolt carriers.
*Armorer Bench Notes & Real-World Staging Guidance:
Fitment Matrix: Direct drop-in fit for standard mil-spec AR-15, M4, and M16 bolt carriers chambered in 5.56x45mm NATO, .223 Remington, and .300 AAC Blackout.
- Verify upper receiver assembly is completely clear, magazine removed, and chamber visually and physically confirmed empty.
- Disassemble your existing bolt carrier group by pulling the firing pin retaining pin, firing pin, cam pin, and factory bolt assembly.
- Lubricate the Geissele Stressproof bolt tail, gas rings, and cam pin journal with quality synthetic weapon grease or CLP.
- Slide the 05-2991 bolt assembly into the front of the carrier body, align the cam pin hole, insert the cam pin, and secure with the firing pin and retaining pin.
- Perform headspace verification with GO/NO-GO gauges when pairing with a newly installed barrel extension.
Key Features
- Carpenter 158+ Forged Alloy: Advanced material composition delivers up to 5x greater fatigue resistance than standard Carpenter 158 steel.
- Stress-Relieved Bolt Lug Geometry: Increased material radius at the lug roots and cam pin bore prevents high-stress fracturing.
- Dual-Spring Extractor Architecture: Proprietary extractor design utilizes dual internal springs to ensure violent shell extraction without rubber inserts.
- HPT & MPI Inspected: Individually High-Pressure Tested and Magnetic Particle Inspected to guarantee zero microscopic material defects.
- Manganese Phosphate Finish: Heavy-duty phosphate coating absorbs oil and resists carbon buildup under heavy suppressed firing.
- Universal Mil-Spec Carrier Fitment: Drops directly into standard AR-15 / M16 carrier bodies chambered in 5.56 NATO, .223 Rem, and .300 BLK.
Product Specifications
- Brand: Geissele Automatics
- MPN: 05-2991
- SKU: 05-2991
- UPC: 815671015693
- Caliber Compatibility: 5.56x45mm NATO / .223 Rem / .300 AAC Blackout
- Material: Carpenter 158+ Alloy Steel
- Testing: HPT (High Pressure Test) & MPI (Magnetic Particle Inspected)
- Finish/Color: Manganese Phosphate Black
- Included Components: Complete Bolt Assembly with Extractor, Ejector, and Gas Rings
