So, I went and made a page:

AR15 Forge Markings

A lot of information is based off these ARF threads:

Some Forge Mark Basics (2014)
Upper Receiver forging mrkings (2014)

I hope that page helps you the next time you're at a gun show and looking at a unlabelled upper or lower and trying to decide whether or not to buy it; and the only thing besides the price tag is some rando marking on it...

AF is actually Accurate Forging.
Acquired by Cerro Fabricated Products in 2000.


Eta: Another for the CAGE marked list:

CAGE: 1KW91
Manufacturing Support Industries Inc.
UEI JARKWEDDKJL4
Division Manufacturing Support Industries, Inc.
DBA MSI

Attached File

Very nice sheet.  Thank you. In case you want more data, I have an AF (Alcoa Forge / Accurate Forging) upper I received from Olympic Arms in 2000

I have a Midwest Industries Upper recently bought with Anchor Harvey forge marks.

You're missing Sigma?
Runic S forge mark.

AIRBORNE!!!!!

Both my Geissele uppers have a G and an open square.

Why does it matter? No really. There are only a handful of forgers who just stamp out a block of aluminum into something resembling an upper or lower. All about about the same quality.
It's the machine shop doing the machining that makes a different. And of course which alloy of aluminum is used and how/if it's heat treated. You could get a dozen forgings from the same place and end up with different levels of quality depending on who does the machining. From tight tolerance (meaning a very small plus or minus from the desired number, a loose tolerance is a larger variation) to some crap like many Olympic Arms were. Or the holes that aren't lined up or the right size, mag wells too tight, not wide enough for a trigger to smoothly fit, etc.

The company that does the machining, or who contracts the machining and sets the specs, is much more important than who's hydraulic hammer smashed a billet of aluminum into a basic shape (billet is just a block of something, it's been used by some AR makers to signify they just machine it from a billet without any forging).

Yup , forge marks matter less than zero , i got wrapped up in it too once , then after reading up on it i realized its like taking two chunks of wood and you have a 8 year old with one , and Louisville Slugger  with the other , now make me a Baseball bat

A machine shop local to me has a license to make lowers, and the the forgings they get have the forge's roll mark one the area the grip attaches to.  The roll mark gets machined off in their finishing process.

They probably mean more to the folks that have to fixture them and machine them. Wonder if there are any they groan about having to use.

Why is cerro forge not associated with colt as well? Most C stamped colt uppers that i have seen in the last 8 or so years also have they keyhole forging

Cerro makes forgings for several. Colt has never been a Cerro exclusive as far as sourcing.  

Most every Colt's upper receiver that I've seen produced recently has been BAFE forged.


Colt/Cerro seemed to come to an end late '16/-early/mid '17. Also about the time that CAGE marked uppers appeared and stamping the "C" became standard.