Ruger Model SR-556, 5.56mm cal. auto rifle. Serial #591-13169. Excellent new in the box condition. 20" barrel has an excellent bore, no sights. Barrel has a 1:8 twist. Full length Pic. style top rail. Ventilated round aluminum hand guard. 100% stainless finish on the barrel and 100% black finish on the receivers with no wear. Has a black textured composite pistol grip and fixed stock. Comes with three magazines. Includes lock, paperwork and factory box with correct label.