RRA Upper Proof Marks

[Spishack357]

Hey all, just bought an RRA upper receiver and was wondering what the designation is to prove its an RRA. It has a square symbol milled into it, I'd appreciate any input.

[Kaos]

Hey all, just bought an RRA upper receiver and was wondering what the designation is to prove its an RRA. It has a square symbol milled into it, I'd appreciate any input.

That would just prove who forged it (assuming it's forged which most are).

Reference reading

here:
http://www.biggerhammer.net/ar15/uppers/

and here:
http://www.thehighroad.org/showthread.php?t=188497

[weaselchew]

Are you referring to an upper receiver or a complete upper? I think RRA marks their barrels at least with a barrel code. I assume it's not an RRA A4/flat top receiver? If it is, they typically have "RRA" or Rock River marked on the top like this one: http://www.coldwarshooters.net/index...roducts_id=171

If it's just a receiver or there are no other markings, you could look for forge markings. Below is a list that has been circulating the 'net:

Forging marks/makers
A (splintered) = Anchor Harvey Aluminum
AF = Alcoa Forge
C AF = Colt Alco Forge
C MB = Colt / Mueller Brass
Cardinal head = Cardinal Forge
CH = Colt Harvey Aluminum
CK = Colt / Kaiser Aluminum
NATO circle cross followed by "AR" = ArmaLite
CM = Colt / Martin Marietta
D = Diemaco
DK = Diemaco / Kaiser Aluminum
E = Emco
EK = EMCO/Kaiser
E MB = EMCO/Mueller Brass
F keyhole = FNMI / Cerro Forge
FA = FNMI / Anchor Harvey
FK = FNMI / Kaiser Aluminum
FM = FN/Martin Marietta
FMB = FNMI / Mueller Brass
Keyhole = Cerro Forge
L = Lewis Machine & Tool
LK = LAR / Kaiser Aluminum
LM = LAR / Martin Marietta
M (under diamond) = Mueller Industries
PA = Capco / Anchor Harvey
PM = Capco / Martin Marietta