The Standard Catalog has a SN index, you can look up approximate manufacture year dates based on a serial number range. A letter of authenticity from the SWHF can tell you the ship date for a particular gun, which may be months, or even several years, from the manufacture date.
Starting around 1980, revolvers started using a three letter prefix, which is confounding to try to get a manufacture date from. Some revolvers still have the single letter prefix into about 1983, but after that, they are all 3-letter. AAA, then AAB, then AAC....AAZ, BAA, BAB..... and so on. The problem is, the 3-letters are not always sequential to the manufacture date, they jump around a lot, and some combinations aren't used.