This is a like new Alexander Arms 16 inch M4 flat-top Upper complete with double heat shield handguards chambered in 5.45x39 (or as Alexander Arms calls it, .21 Genghis). Maybe 300 rounds through it. Bolt was made by Les Baer. Takes standard AR15 mags with black followers. Comes with the original Alexander Arms magazine still in wrap.
$550 shipped insured without sights
If you wish it is also available with a RRA's detachable front sight and an Arms 40 sight for $650 shipped.
Not interested in trades unless it is for a 9mm AR setup.