Forgive me if this is an obvious answer.  I did a search, but didn't come up with anything (both here, and google).  
I recently purchased an AR-15 upper (16" Midlength A2) from M-AParts.com and the upper has an maker marking that looks to be a keyhole.  The barrel isn't marked, and I was wondering who made it.  Just for reference, no other reason.  Also, is there a place where somebody has already compiled all of the maker markings so that I don't have to bug you guys with minor questions?  Thanks!

Brian

Its the forging mark of Cerro Forging www.cerrofabricated.com/

Wow,never would have guessed that one!  Who markets the Cerro Forging products?  I had never heard of them prior to this.

Brian

I believe they make raw forgings for all the big companies, CMT, Colt, Bushmaster....... etc.

I have 2 bushy with the key hole

www.ar15.com/forums/topic.html?a=subscribe&b=3&f=12&t=223495&sub=Lower+Receiver+%26+Mag+Floorplate+Rollmarks%2C+Logos+and+Markings

Quoted: www.ar15.com/forums/topic.html?a=subscribe&b=3&f=12&t=223495&sub=Lower+Receiver+%26+Mag+Floorplate+Rollmarks%2C+Logos+and+Markings

Excellent!  The topic ended over 30 days ago, no wonder I never came up with anything!

And to the rest of you, thanks for the input!  I guess the keyhole doesn't signify who marketed it like I hoped it would.

Brian