I have several S&Ws that I bought new & which I still have my purchase paper work for. Several made visits to the Springfield Service Center around 1977-79. Are there records confirming what was done.
For instance my service 19-3 had the barrel turned in a turn to correct the gap. Triggers fitted. A couple of years later, I had the front sight changed to a ramp on 25-2. But I didn't keep records of it, if there even were any.

I would bet they do and that is exactly how they letter our guns. That said, I sincerely doubt they would do the research and put it in writing without a handsome charge, as it might take some time and effort to dig them up.

There would have been a receipt or work order documenting these repairs or modifications, but they may have been destroyed after a certain time. Such records from the 1930s have been digitized, but doing this for later ones would be a major undertaking, perhaps millions of pages, if they still exist. The early records will not be noted in factory letters but if available the earlier ones can be accessed via the S & W Historical Foundation if you already have the factory letter.

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Alan
SWCA LM 2023, SWHF 220