Product Features & Specifications This AR-15A4 Semi-Automatic Colt Rifle is a throwback to the full size AR-15(R) which gave birth to the Modern Sporting Rifle. The AR15A4 is defined by it's 20" 1:7 Twist Government Profile Chrome Lined Barrel and A2 Fixed Buttstock. The rifle is topped with a Picatinny Flat Top Upper Receiver with Detachable Carry Handle. Caliber: 5.56x45mm NATO/.223 Remington Barrel Length: 20" Bore: Chromed, 6 grooves, 1-7" RH Twist Front Sight: A2 Fixed Front Sight Post Rear Sight: Detachable Carry Handle A2 Sight Extended Length: 35.5" Collapsed Length: 32" Weight: 6.9 Pounds Action: Manual Direct Gas System, Locking Bolt Finish: Matte Black SKU: AR15A4 UPC: 098289023292