Preowned – Centurion Arms CM4 chambered in 5.56. This is a custom build w/ a Centurion upper and lower receiver, Sionics 16″ barrel, Sionics BCG, BCM MCMR-15 rail, Plan B flash hider, Kratos gas block, Larue MBT curved trigger (trigger has been spray painted), BCM pistol grip, A5 buffer system, B5 stock, Geissele Super Charging Handle, FCD magazine release, FCD Low Snag Forward Assist, and Geissele Maritime Bolt Catch.