Ruger’s Ar-556 is made from aerospace-grade 7075-T6 aluminum forging, the flattop upper receiver includes a forward assist, dust cover and brass deflector, and is Type III hard coat anodized for maximum durability. Six-position telescoping M4-style buttstock and Mil-Spec buffer tube allow the rifle to be properly sized for different shooters, or varying levels of outerwear or defensive gear. Medium contour cold hammer-forged barrel with ultra-precise rifling provides exceptional accuracy, longevity and easy cleaning. The 1:8″ twist rate stabilizes bullets from 35 to 77 grains, and the 5.56 NATO chamber allows the use of both 5.56 NATO and .223 Rem. Ammunition. M4 feed ramps provide improved operational reliability, and the matte black oxide finish reduces glare and provides corrosion resistance. A Ruger® flash suppressor is provided, and the 1/2″-28 threaded barrel allows for standard muzzle accessories to be installed.