Grey Ghost Precision Forged Upper Receiver AR-15 5.56x45mm NATO M4 Hard Anodized Finish Black. Ask and ye shall receive Finally you can grab what we consider the best forged upper in the biz and it is a perfect companion for your GGP Cornerstone Lower receiver. After all accuracy comes from tight precise tolerances that minimize all variables from the moment the hammer strikes the firing pin until the round leaves the muzzle. By perfecting the critical tooling dimensions to the smallest degree a forged receiver can punch the same hole down range. Specifications for Grey Ghost Precision Forged Upper Receiver: Manufacturer: Grey Ghost Precision Color: Black Finish: Hard Anodized Fabric/Material: Forged 7075-T6 Aluminum Caliber: 5.56x45mm NATO Gun Make: AR Platform Gun Model: AR-15 Condition: New Barrel Profile: M4 Gun Type: Rifle Weight: 0.4 lb Features of Grey Ghost Precision Forged Upper Receiver Machined to tighter than Mil-Spec tolerances the critical tooling dimensions are held to within +/ - .001in Machined from forged 7075-T6 Aluminum Black Hard anodized with a surface hardness of 60 Rockwell M4 Feedramps .250" Takedown pin holes Engraved T-marks Functions with nearly all available AR-15 parts kits and lowers Match with our Cornerstone lower receiver for a solid and dependable fit Stripped Receiver DOES NOT include port door forward assist or any small parts Package Contents: Grey Ghost Precision Forged Upper Receiver What firearm models does the manufacturer say Grey Ghost Precision Forged Upper Receiver is compatible with? The manufacturer says that Grey Ghost Precision Forged Upper Receiver is compatible with AR-15Grey Ghost Precision GGPC-UR: Forged Upper Receiver AR-15 5.56x45mm NATO M4 Hard Anodized Finish Black