GC_UPC Aero Precision M4e1 Assembled Upper Receiver Threaded 5.56mm Fde - Ar-15 M4e1 Assembled Upper Receiver Odg 5.56 W/M16 Cut $159.99 APAR700220AC show more like this $12.50 Brownells GC_UPC Aero Precision M4E1, Assembled Upper Receiver, Anodized Finish, Olive Drab Green, Fits AR15 APAR700220AC MAP APAR700220AC show more like this Flat Rate Starting at $11.99 Hinterland Outfitters