I'd guess maybe 1947 or 48, the last ones were in 1948 at S999999 with the first in 1946 at S811120, according to the 4th Edition of the S&W Standard Catalog. You'd need a letter to know the exact date and a letter would tell you to where it originally shipped. Nice gun, I like the MOP grips and holster too. I have S837418 which shipped in June of 1946. Maybe JP@AK will be along with more information, he's the guru on these. Welcome to the Forum.
Jeff
SWCA #1457