GC_UPC Aero Precision M4E1 Threaded 20" .350 Legend Carbine Length Complete Upper Receiver with 16.6" ATLAS R-ONE Handguard - Anodized Black - APAR700106M100 $674.99 APAR700106M100 show more like this Calculated in Cart Classic Firearms GC_UPC Aero Precision M4e1 Threaded 350 Legend Assembled Upper Receiver - M4e1 Threaded Assembled Upper 350 Legend 20" Qpq Carbine Blk $674.99 APAR700106M100 show more like this additional Brownells