So a friend of mine was showing me his complete GM upper and we took the handguards off to see the markings. I've never seen these types of markings before so I was wondering if anyone knew the origin of these. I know the typical GM markings have a number with the + or clover symbol. He has had this upper for roughly 20 years and never had the handguards off and it took us about 20 minutes to get them off which makes me think they never left the barrel.  FWIW  his GM upper is complete including the BCG and charging handle.  Is it possible that GM used a different sub contractor for the handguards or is his upper only 99% original. The same marking is on the other handguard as well.



A view from a different angle looks like a reverse 5

Cool, I have never seen that.  Can you post pictures of the complete upper?

It's about 50 miles away from me at this point. It's just a regular GM complete barreled receiver with normal rear flashing and glossy black original finish. I would have taken more pictures but his is basically the same as I have. The cool thing is that he may part with it so I got first dibs on her!

there's the fat grips that have numbers as well instead of the plus/cross symbol.  maybe same sub?

Perhaps. Funny thing I noticed about the heat shields was that the right heat shield was proudly stamped R but the left heat shield has what looks like a reverse L stamped on the side of the heat shield facing inwards towards the HG. It's in the proper place where it would normally go but on the other side and reversed. WTF?

i have a few reverse stamped sets.  they seem to be made of a denser material.  noticeably heavier.

I think it is worthwhile to post pictures of the non Colt parts because we still don't have a very large sample size.  For example, this might be the first time someone posted this marking on a hand guard.    I suspect there are s few surprises waiting out there, I wish people would post more pictures since we all like seeing them.