Daniel Defense M4A1 Semi-automatic AR, 223 Rem/556NATO, 16 (14.5 with Pinned Brake) Hammer Forged Barrel, Flat Dark Earth Finish, 10Rd, Daniel Defense Furniture, California Compliant 02-088-06027-055 The Daniel Defense M4A1 features the M4A1 RIS II, which has been in use by US Special Operations Command (SOCOM) for the SOPMOD II Weapons System since 2005. The M4A1 features a 14.5" Cold Hammer Forged M4 Profile barrel with a permanently attached Daniel Defense Flash Suppressor.