I'm in the final stages of piecing together a poor man's SPR from scratch. I've got just about everything but optics and a M4 upper receiver.
While shopping around for uppers I noticed a pretty sizable difference in prices. A stripped Wilson goes for roughly $140. A LaRue for about $230. Vltor for about $250.
I also noticed that Bravo Company USA is selling a generic one for about $85. From what I can see in the pictures, it has the keyhole (Cerro Forge?) marking. I assume that means Cerro Forge kicked out a machined blank to some random manufacturer, who then finished it.
Upper Receiver Assembly - M4 Flat Top
So whats the difference between the $85 generic upper and a Wilson?