Ruger's AR-556 semi-automatic rifle is made from forged aerospace-grade 7075-T6 aluminum. The hard coat anodized, flattop upper receiver includes a forward assist, dust cover and brass deflector, while the handguards are made from heat-resistant glass-filled nylon. It has a carbine-length, milled gas block with multiple attachment points for a QD socket, bayonet lug, and sling. Serrations on the angled face of the gas block provides a low-glare surface. It also has a bolt machined from 9310 alloy steel, single-stage trigger, chrome-plated bolt carrier with a matte black oxide finish on the exterior, and patent-pending barrel nut and Delta ring for one person handguard removal and installation.