Hey everybody, I'm trying to figure out the forge codes on my new Colt 6721 upper.  They are like nothing I've ever seen before and I've looked around everywhere and can find no reference to these.

Colt 6721 / SN LBD025XX0

Unfortunately, I cannot post pics right now, so I'll describe them as a appearing on the right side of the upper, aft the brass deflector.

The first stamp is what appears to be the outline of a Keyhole, the second is what appears to be the rough estimation of the letter "A," but as though it were knocked over onto it's right side.  Also the A is not exatly an A but more of an a without it's "feet" or the Letter "V" with a slight curl on the left diagonal arm.

Hope this makes sense.

Those are commonly seen markings

The A is an Anchor Harvey code



the Keyhole is a Cerro forging mark



Others can be seen ----------> _DRs lowers and markings thread - see upper markings

also, Biggerhammer.net

The A with out legs that's knocked onto its right side might be for "Diemaco", who would be the company that machined and finished the receiver...

The key hole symbol stands for "Cerro Fabricated Products", who would be the company that forged the receiver...


Looking at the picture below, does the mark look like the one on the left?

Quoted: Those are commonly seen markings The A is an Anchor Harvey code www.chameleonweaponry.com/dr-arf/UM_ANCHOR_HARVEY_ALUMINUM.jpg the Keyhole is a Cerro forging mark www.chameleonweaponry.com/dr-arf/UM_COLT_CERRO.jpg Others can be seen ----------> _DRs lowers and markings thread - see upper markings also, Biggerhammer.net

He wouldn't have two forging manufatures on the same upper so I don't know why this is posted.

It is obvious his upper is a Diemaco/Cerro upper from his description.