Guntec USA AR-308 Cal Firing Pin Retainer Black. 308 Winchester Gun Make: AR Platform Gun Model: AR308 Gun Type: Rifle Hand: Ambidextrous Projectile Caliber: .308 Caliber Features of Guntec USA AR-308 Cal Firing Pin Retainer Mil-Spec Package Contents: Guntec USA AR-308 Cal Firing Pin Retainer What firearm models does the manufacturer say Guntec USA AR-308 Cal Firing Pin Retainer is compatible with? The manufacturer says that Guntec USA AR-308 Cal Firing Pin Retainer is compatible with AR308Guntec USA GT-FPR-308: AR-308 Cal Firing Pin Retainer Black