Olympic Arms 16 inch XM177 type upper assembly. A1 upper w/Teardrop Forward Assist, Barrel marked “5.56”. Barrel is 11.5” with 5.5” perm attached Flash hider which is the correct diameter to allow a Bayonet to be mounted. I believe this is the mid/late 80’s production with the Plastic Delta Ring, cheesy but works! Rapidex knob installed for easy windage adjustments. Well used condition but still shoots straight and functions fine. Front sling swivel needs a new pin to be tighter. I’m asking $260 shipped/Insured via Priority Mail. Payment by US Postal Money Order only.