- VERY GOOD CONDITION - NO BOX - NO MAGAZINE - AIMPOINT COMPM4 RED DOT - premium AR-15 style rifle featuring a reliable short-stroke gas piston system. It fires a hard-hitting 6.8mm cartridge for superior knockdown power compared to standard 5.56mm. Built with a cold hammer-forged, NiCorr-treated barrel, it runs cooler and cleaner than traditional direct-impingement rifles. - 6.8 MM