Noveske Rifleworks Gen 4 N4 SPR Stainless 6MM ARC Complete Upper Receiver - 18" - Bazooka Green

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

Wraithworks Billet Slick Side AR-15 Upper Receiver - Black | No Forward Assist or Brass Deflector

BEAR CREEK ARSENAL 5.56 NATO COMPLETE UPPER 10. BRL 1:7 TWIST CARBINE LENGTH GAS MLOK

TACFIRE AR-15 Billet Slick Upper Receiver Black

Sons of Liberty Gun Works L89 Combat V2 AR-15 13.7" Pinned CMV 5.56 NATO Assembled Upper Receiver w/ NOX-9 Flash Hider

Sons of Liberty Gun Works SOLGW 14.50" Upper 5.56x45mm M-LOK Rail - Tactical Excellence - M4L89BSCHF14.5

CMMG Banshee Mk4 AR-15 Upper Group .338 ARC 10.5" Barrel Black