The Aero Precision EPC/AR9 Bolt is the core of your EPC build. Machined from 8620 steel and featuring a nitride finish, fracture resistant grade 23 titanium pin, and 4140 steel extractor, the EPC bolt assembly is precision machined from the ground up to meet the extreme demands of blowback AR platform firearms. BOLT FEATURES: Machined from 8620 Steel Black Nitride Finish BOLT INCLUDES: 8620 Steel Bolt Assembly 4140 Steel Bolt Guides Grade 23 Titanium Firing Pin Firing Pin Retaining Pin 4140 Steel Extractor Heavy Duty extractor coil pin (all parts are installed)