I just got my olympic varmint upper and the only marking on it is a raised symbol less than 1/8" tall on the right side just behind the deflector that looks like a keyhole.
Sorry, but this doesn't sound like a factory Oly upper. If there is a mark behind the deflector, it's not likely an Oly upper.
Springs, and pins and plastic furniture is about all they outsource. All major components (including CNCing recievers) are done by them unless something has changed very recently (which I doubt).
What model upper do you think you have? Where did you buy it? What is the barrel stamping just forward of the gas block? Any other marks or stampings on the reciever or reciever lugs?
Pics would help determine the actual make (unless it's a frankenAR and just sold as an Oly brand). In which case I would be contacting the seller for misrepresenting his products as it would not be covered by the lifetime warranty.
Here is a closeup of an actual Oly upper shipped straight to my doorstep in Oct '04 from the factory. (*note no mark behind the shell deflector)
Depending on the barrel model, it may be stamped: SUM + the barrel twist if it's a broach cut barrel (.223 only here),or for barrels like all their M4 barrels will be stamped: SS indicating stainless (shown below).