The world of .308 caliber ARs can be confusing. Unlike the AR-15, .308 AR rifles come in a variety of patterns. We have free-floating handguards to accommodate any AR-10 platform. Our STAR series quad rail is available for Armalite AR-10 pattern rifles and uses a factory barrel nut. Our Evolution system is a modular, free-float design that is available for DPMS LR-308 pattern rifles, DPMS GII pattern rifles, and the Adams Arms SF-308. These rails either ship with an included barrel nut, or use the factory supplied barrel nut.