That doesn't work for me, Jason. But I'll explain why and you can draw your own conclusions.
First of all, the "AC" tools I think you're talking about were made by Wright, not Plomb. I was the one who first postulated that the "AC" on the Wright tools stood for "Air Corps," but it's important to recognize that it wasn’t as simple as an unsubstantiated guess (i.e., A for Air and C for Corps). I made the postulation based on the fact that Wright had contracts with the US Army Air Forces that coincided with the dates codes we were seeing on the tools, and - this is the key, that those contract numbers, encoded with the contracting agency, all started with "AC".
The "AC" was used as the code for all US Army Air Forces contracts because many contracts in the book (which start in June 1940) pre-date the existence of the US Army Air Forces, which was established - due to a squabble about who had control of strategic bombers, in June 1941. Prior to the USAAF, there was only the US Army Air Corps. In other words, when those early contracts were awarded, they were truly awarded by the Air Corps. When the USAAF was established, and the Air Corps was subsumed underneath the USAAF, the contract numbers did not change. And when the book was published, in late 1945, by the Civilian Production Administration (new, post-war name for the War Production Board), the index accurately indicates that "AC" was the code for USAAF contracts.
Secondly, unlike the Wright "AC", identifying the customer, accompanied by an explicit numerical date code (e.g., "43"), identifying the date of production, the "MC" on Bill's Plomb ratchet (and the “”UC” and “VC” on oldmantaylor’s Plomb tools) most closely resembles the two-digit alphanumeric system that Plomb used as a date code to indicate date of production.
Thirdly, keep in mind that Plomb also had contracts with the US Army Air Forces, specifically with the Air Corps, and its contracting agency was located at Wright Field, which they used in short form ("WF") to indicate the same customer that Wright had. Without any documentation specifying how to mark their tools, it looks to me like Wright and Plomb took different approaches.
Finally, the Marine Corps belonged to the Navy, and Navy contract codes all started with an N. Plomb had several Navy contracts, with Aeronautics (NXSA), Ships (NXSS), and Supplies & Accounts (NXSX). None with the Marine Corps (NOM).
EDIT: For the Jeep guys out there, if you’ve ever wondered how or why Willys used “NOM” as a designator for the MB’s it built for the Marine Corps, that’s why.
. Now I need someone to post a good dual mark photo so I can make stickers ?!!
