identifying AR upper?

[Acolyte]

Hi all,
I've got an AR with a mystery upper ...
the lower is Rock River - I emailed the serial to rock river, and they said it was sold to a local gun shop some years ago.
I look up the gun shop - they're out of business now.
Is there any way to identify who the manufacturer of the upper is?

These are the markings I can see:

- on the right side of the top of the carry handle, just in front of the windage knob, there is the letter "A"
- in the lower horizontal bar of the front sight tower, there's what appears to be the letter "F" that looks _somewhat_ reverse-embossed in a 'square', followed by an "R1" embossed in a 'circle', followed by a "2" (with no shape)
- at the top of the tower, right behind the front sight post, there's the word "UP" (although I guess this is probably a standard marking)
- no markings on the barrel from what I can see
- I removed the handguards, and the rear portion of the barrel isn't marked, nor are the handguards

I interested because I want to know the twist rate, steel grade, and if it's chrome-lined or not.

This site (http://www.biggerhammer.net/ar15/uppers/) says a 'splintered A' production code mark (the mark in front of the rear right) means Olympic Arms ... how is the 'A' 'splintered'?

Thanks in advance!

edited to add: this site (http://www.oa2.org/forums/viewtopic.php?t=1487) says that Olympic stamps a letter on the rear locking lug, and I couldn't find anything stamped on either of the two lugs

 

[Bartholomew Roberts]

The marks you are describing are forge marks and in most cases will only tell you who produced the raw forging, not who manufactured the final upper (there are exceptions as Colt and Diemaco both mark their raw forgings).

Does your A have a small line through it (kind of like an A on top of an H?) - if so that is the forge mark for Anchor Harvey.

All in all, knowing the forge won't help you much since many different AR manufacturers use the same raw forgings. Even if you can trace it down to a single manufacturer, no guarantee that the rest of upper (barrel for example) came from them as well.

The markings on the front site tower are pretty common to several manufacturers.

 

[Harry Tuttle]

heres another forger:
http://www.cerrofabricated.com/products_firearm.htm