Win-13...how rare are these in the wild?

[csm14thbn]

I have a few WIN 13’s and i have been looking for the SA matching serial number for years and no luck so far. the closest i have found is about 200 off in the number. There is a lot of speculation as to why WIN used the wrong serial number but i doubt we will ever know for sure. SA had been assigned that serial number range in 1943 then WIN used 1,600,000-1,640,xxx in 1945 when it looks like they should have been using 2,600,000-2,640,XXX.