What stock stamp is this?

My mind is playing tricks on me. I can't remember what stock stamp this is. Can someone help me? I think it shows a box w/"RTA" and below it a "FR"

https://scontent.fcxo1-1.fna.fbcdn.n...DA&oe=6536EA51

Possibly but I read it as;
RIA
FR = Factory refurb

Stolen from CMP I think, "This mark is an RIA-EB mark. I have it on good authority that this is a rebuild mark for the Rock Island Armory."

It looks to me more like the "FK"...

[2003 Note: According to Bruce Canfield - The "EB" marking represents Elmer Milton Bjerke. He went to work at Rock Island Arsenal on February 20, 1939 as a classified laborer assembling small arms. In September of 1940 he was promoted to Shop Inspector under the supervision of Frank Krack ("FK"). During WWII, Bjerke was one of many inspectors working at RIA. On January 6, 1947 Bjerke became Foreman of Small Arms Inspection and his "EB" cartouche began to be used. He held this position until 1958. Therefore, the "EB" marking indicates that the weapon was overhauled at Rock Island between 1947 and 1958.]

So it's a RIA with an FK .

I think so...

It is the RIA FK which started at the start of WW2 and replaced by RIA EB just after WW2Attachment 133464