The closest would be the year of 1949, but so many were reworked and the later series built to smaller batch orders, it is beyond me to say which month, or season for that matter.
Thank you Marine. Does the receiver stamping read MF,"E",MF,L,M or "E",L,M,G? The first indicated ManuFrance assemblage, the latter is St Etienne. What is the difference? Well aside from the trivia of it all, ManuFrance was the more common among the pre-Armistice "K" block, but the minor assembler over all, responsible for perhaps 30,000 of the 250,000 that were produced before June 22, 1940. (This disregards the "F" series, the numbers and fate of which are unknown)I don't know if this helps, my s/n is K10811 and was made in June 1940.