Geissele Automatics Stress Proof Bolt Assembly Features The Geissele Automatics Stress Proof Bolt Assembly is forged from Carpenter 158+ steel a material developed in direct collaboration with Carpenter Steel metallurgists specifically to reduce impurities compared to standard bolt steel. That cleaner material composition is what gives this bolt its fatigue resistance allowing it to withstand far more firing cycles before showing wear than a typical mil-spec bolt. Geissele states the bolt is capable of five times the service life of standard components a meaningful advantage for shooters who put high round counts through their rifles. The bolt is featured in Geissele s own Reliability Enhanced Bolt Carrier Group underscoring the company s confidence in its durability. Every Stress Proof Bolt undergoes rigorous inspection before it ships including high-pressure testing and magnetic particle inspection to catch any hidden flaws in the forging. The bolt also receives a Nanoweapon coating which improves lubricity and corrosion resistance for smoother cycling and easier cleaning after heavy use. It includes the extractor so the assembly is ready to install into a compatible AR-15 bolt carrier group without hunting down additional parts. For shooters upgrading an existing build or assembling a new rifle from the ground up the Geissele Automatics Stress Proof Bolt Assembly is available for sale at GrabAGun as a proven thoroughly tested component. Geissele Automatics Stress Proof Bolt Assembly Specifications Manufacturer: Geissele Automatics Model: Stress Proof Bolt Assembly Type: Bolt Compatible Hosts: AR-15 Color: Black Material: Carpenter 158+ Steel Available At: GrabAGun