Fifth
I copied the above list of US Military Wristwatch Specifications from the Military Timepiece Section of IHS185 in a discussion by world renowned collector of military watches (one of a few to have collected the "Dirty Dozen") It is only a quick reference list to look up mil-specs. Very unintersting reading those mil specs. I must say It lists the spec number & the date the spec was approved & for what specific watch.
It is not a contract between the government & manuufacturers. It only shows that by checking the spec on the back of the Type A17, MIL-W-6433A immediately above, could not have been contracted for before the spec date of 4 August 1960. So the date symbol L6 on the 10BNCH tells me that backcase & movement DO NOT belong together. This 10BNCH movement is likely to be MIL-W-3818A dated 1956 (L6 as stamped).
I doubt very much there is a typo on the list & I seriously don't think there is an error of omission that your so called 1950 Korean War watch is not included on the list.
CORRECTION: typed in bold