E Prefix Underwood

Greetings, I am new to the forum and not very knowledgeable about M-1 carbines (mostly Smith and Colt revolvers). I recently acquired an excellent Underwood. The little research I have done indicates that about 20 E prefix guns are known, with serial numbers below E300. Explanations offered on various sites refer to them as experimental, presentation, or (most commonly) assembled from left over parts and presented/sold to employees after the war. I have not disassembled my gun, but see not visible markings on the metal or wood other than behind the rear sight.
Any information would be appreciated.

Thanks,
Bob
https://www.milsurps.com/images/impo...p3lsamol-1.jpg

Bob, not a lot of info out there known about E Underwoods. PM sent.