5.56 NATO

HM Defense / Luxus Arms

LUXUS ARMS HM Defense 16MBUP556L MonoBloc Upper Assembly for AR-15 in 223 Rem & 5.56 NATO, 16 Inch Black Cerakote Barrel

Daniel Defense

Daniel Defense DDM4 V7 LW URG 5.56 NATO Accessory Upper Receiver with 16-Inch Barrel

Daniel Defense

Daniel Defense DD4 RIII URG 5.56mm Accessory Upper with 12.5-inch FDE RIS III M-LOK Rail

Daniel Defense

Daniel Defense DD4 RIII URG 5.56mm 11.5-inch FDE Matte Black Upper Receiver

Daniel Defense

Daniel Defense MK18 Upper Receiver in Flat Dark Earth with RIS II Rail

POF USA

POF USA Renegade+ Upper 5.56 NATO, 16.5-Inch Black Anodized with M-Lok Handguard

POF USA

POF USA P-415 EDGE Upper Receiver 5.56 NATO with 14.5-inch M-Lok Rail and Short-Stroke Piston

POF USA

POF USA P-415 EDGE Upper Receiver for 5.56 NATO with 10.5-Inch Barrel - Black Anodized Finish

POF USA

POF USA Renegade+ Upper Receiver for 5.56 NATO - Black Anodized Finish

Heckler and Koch (HK USA)

Heckler & Koch MR556A4 URK Upper Kit 5.56mm with M-Lok Handguard

Bushmaster

Bushmaster XM-15 QRC Upper Receiver for 5.56 NATO and .223 Rem with Salt Bath Nitride Finish

Bushmaster

Bushmaster Patrolman Flat Top A4 Upper Receiver 16-inch for 223 Rem / 5.56 NATO