The M4A1 AR15 style firearm features the RIS II picatinny quad rail, which has been in use by US Special Operations Command (SOCOM) for the SOPMOD Block II program since 2005. The M4A1 is built around a 14.5 inch Cold Hammer Forged M4 Profile barrel with a permanently attached SilencerCo 3 Prong Flash Hider. The independently ambi GRIP-N-RIP Charging Handle accommodates left- and right-handed shooters. Specifications and Features: Manufacturer: Daniel Defense Model: M4A1 Caliber: 5.56 NATO Mounting System: Picatinny Caliber: 5.56mm NATO Muzzle Thread: 1/2 28 TPI (Threads Per Inch) Gas System: Carbine Barrel Length: 14.5" with Pinned and Welded Muzzle Brake Barrel Profile: M4 Product Weight: 6.74 lbs Length: 31 1/2" 34 3/4" (w/ muzzle device) Magazine: DD Magazine Case: Daniel Defense Full-Latch Impact Plastic Case Manufacturer: Daniel Defense