V Seven Gi Heavy 556/223 Complete Upper 16in 16HR GI-UR. I. Heavy GI-series complete upper assemblies are machined with an enhanced lightweight one-piece bolt carbine profile. The uppers are full auto style so the only carbine components you need to change out are the standard front and rear grippers. This complete upper includes the GI Heavy profile bolt carbine buffer carrier assembly forward assist with ejection port cover bolt carrier key and forward assist gas port cover gas adjustment screw and spring. The bolt carrier key is a one piece polymer material that is forward indexing and acts as a mechanical anti-rotation pin. This upper receiver assembly will fit any standard AR-15 pattern upper. Specifications for V Seven Gi Heavy 556/223 Complete Upper: Manufacturer: V Seven Caliber: 5.56x45mm NATO .223 Remington Overall Length: 33 in Muzzle Device: Muzzle Brake Finish: Anodized Color: Black Gun Type: Rifle Gun Model: AR-15 Weight: 67 oz Magazine Included: No Package Contents: V Seven Gi Heavy 556/223 Complete Upper What firearm models does the manufacturer say V Seven Gi Heavy 556/223 Complete Upper is compatible with? The manufacturer suggests that V Seven Gi Heavy 556/223 Complete Upper is compatible with AR-15V Seven 16HR GI-UR: 16" Gi Heavy 556/223 Complete Upper