Unknown 5.56mm Upper Receiver with 10.5 Inch Barrel (No Charging Handle or BCG)

Faxon Firearms Mid-Length Button Rifled Gunner Barrel 5.56x45mm 16", Black

AERO PRECISION AR15 5.56 NATO / 223 Rem 20" Complete Upper Receiver w/ Carry Handle | Black

Radian Weapons R0027 Complete Upper 300 Blackout 9" Black Barrel, 7075-T6 Aluminum Radian Black Receiver, Extended with Magpul M-LOK Handguard for AR-15

BUSHMASTER M4 Type Patrolman Flat Top A4 Upper 5.56 16" Black

BATTLE ARMS Workhorse Upper Recv 5.56 16" AR-15 Sniper Gray

BATTLE ARMS Authority ELite Upper Recv 5.56 10.5" AR-15 Gray

AERO PRECISION M4E1-T 5.56 NATO 11.5" Complete Upper Receiver | Black