DoubleStar DS-4 AR-15/M4 Flattop Upper Heavy Match Barrel 16 inch 5.56/.223 1-9 Twist A1 Muzzle Device Black ARBU404. 5.56 Nato 1.9 twist M4 Feed Ramps Forged upper Specifications for DoubleStar DS-4 AR-15/M4 Flattop 16" Upper Receiver:...
DoubleStar DS-4 AR-15/M4 Flattop Upper Heavy Match Barrel 16 inch 5.56/.223 1-9 Twist A1 Muzzle Device Black ARBU404. 5.56 Nato 1.9 twist M4 Feed Ramps Forged upper Specifications for DoubleStar DS-4 AR-15/M4 Flattop 16" Upper Receiver:...