Ruger SR-556 Piston AR-15 556 Rifle.

This is a legendary classic premium AR. One of the first and best piston operated. Cold hammer forged fluted barrel. 3 setting adjustable gas block. Chrome BCG. Flip up iron sights. Shoots excellent. Comes with case and mag. Has not been shot much. Thoroughly cleaned and lubed. These were over $1,500 10 years ago.