<p> The Ruger® AR-556® Semi-Auto Rifle operates with a traditional, direct-impingement system. A 6-position M4-style buttstock allows rapid adjustment according to the clothing and tactical gear the user wears, or for moving from open environments to tight quarters. The standard tactical handguard is made from heat-resistant, glass-filled nylon. The medium contour cold hammer-forged barrel has a 1:8 twist rate that stabilizes bullets from 35 to 77 grains. A Ruger flash suppressor is attached to the barrel with a 1/2-28 thread. The barrel nut and delta ring are designed for 1-person removal and installation of most standard carbine length handguards. The anodized flattop upper receiver is made from aerospace-grade 7075-T6 aluminum, and includes a forward assist, dust cover, and brass deflector. The Rapid Deploy folding rear sight adjusts for windage and elevation, and folds out of the way when optic sights are used; the A2-style front sight post is elevation adjustable (includes front sight tool). The Ruger AR-556 Semi-Auto Rifle comes with one 30- or 10-round magazine. Operates with 5.56 NATO or .223 Remington ammunition.</p> <ul> <li>Operates with direct-impingement system</li> <li>6-position M4-style buttstock</li> <li>Heat-resistant handguard</li> <li>Medium contour barrel</li> <li>1:8 rifling twist </li> <li>Anodized flattop upper receiver</li> <li>Forward assist and dust cover</li> <li>A2-style front sight</li> <li>Folding rear sight</li> </ul>