Looks like a key hole - inside there are three dots  - vertical.

Quoted: Looks like a key hole - inside there are three dots  - vertical.

Try here: www.ar15.com/forums/topic.html?b=3&f=12&t=223495

Looks like maybe the 3rd down on the UPPER RECEIVER MARKINGS list.

Looks like it is probably the CERRO Fabricated mark -----

Quoted: Looks like it is probably the CERRO Fabricated mark -----

Yes, it's Cerro---BUT THEY DIDN'T MAKE THE UPPER!!!

Sorry to shout, but it does get a bit tiring to see people asking the same damn question over and over and over again.

That is a forge mark, to indicate who produced the raw forging  but every manufacturer uses the same few forges for their raw pieces,----so you still don't know who made the damn thing.

Colt historically has had an indicator on their uppers, as to it being one of their products---but no other maker, to my knowledge, does so.


And if you'd done a search before posting, you'd have learned this from past threads--and I wouldn't have shouted at you