OK guys tell me what this is. Its a flat top upper .The only markings that I could find is on the ejection side at the top it has two letters. A ( standard  ) letter C . And spaced over from the C is a weiord looking F or either an A It could be either one by the way its designed. I was thinking Century Arms but Im not familier with them. If you can I.D. it can you tell me if its junk or not...Thanks WarDawg

A "C" with an "A" blended with a "F", would be a Colt unit produced by [url=alcoa.com]Alcoa Forge[/url]

notack is correct.  It is a Colt receiver.  See if it has M4 feed ramps and a "4" or "M4" over the hole for the gas tube.

[img]http://www.biggerhammer.net/ar15/uppers/colt_flattop_proofmarks.jpg[/img]

Thanks guys. What the deal is its a rifle that my cousin bought this past summer. He got it at an auction from a ( SOG )  Army Sgt that died. He had just got back from Afganistan from a tour.The money is going to the children of the SGT. :(    . But this is what it has on it. Its a M4 type rifle.It has a Colt lower, A Colt upper (according to you guys). Has a weirod lookin muzzel break on it. Has a nice CAR type adjustable stock.Has A2 type rear site on the flat top rails. One of them military type 3 point slings with the Knight front sling holder through the front sight base.Has also the Knight Armament picananny type front hand guards with the Knight round cover that snap over the rails when not in use.It also has a  Knight forward handle on the bottom rail on the front hand guards.He paid $700  I think he got a steal. Thats what they was asking. I looked it over and it hardly seems to be fired.We hope to take it out this week. Thanks for the info guys,WarDawg