Plomb Letter Stampings Study
Given the examples below posted thus far, a clear pattern is emerging regarding the 2 letter stamps.
--- We have yet to find any examples disproving this theory. If we discount the "NR" code as a whole different meaning (we believe it represents something different because you will see some examples with both a date code and the NR code), an oddball "single X" and oddball "single O" stamp, it appears the second letter in the codes follows a pattern of A, B, C, D, and E stampings. Early on we theorized that the letter stamps could represent wartime only produced tools. Supporting this theory is the fact that most tools are stamped B, C, or D while A and E are less common second letter stamps. If we assign 1941 to A, 1945 to E, and the B, C, D accordingly, that trend would make sense based on the U.S. involvement periods in WWII. As of now, we are assuming the first letter of the Letter-Letter codes represent a production month. There were still the traditional Number-Letter codes before the U.S. involvement in the war in 1941, as well as in 1945, but we have found no examples of 1942, 1943 or 1944 Number-Letter codes. We have however uploaded examples of 1945 Number-Letter coded tools and it appears 1945 is the final year for date coding until the 1970's.