Buick
Letter that gun! There is a very high likelihood it was one of the 2" round butt M&P revolvers that shipped in August and September of 1946. An unknown quantity of those units had prewar serial numbers in the 694xxx range.
Contemporary production 2" M&P revolvers were in the S833xxx range. At least 100 were made in that run. What we don't know for sure is how many of that 100 (if any) were actually prewar frames. All we know for certain is that some prewar round butt frames and some postwar round butt frames were assembled with 2" barrels and shipped at about the same time. 10 of the units went to a distributor in Seattle. Others went to various distributors around the country. At least one ended up in service with the Boston Police Department.
If you have indeed located one of these special revolvers, you are a very fortunate man. Early postwar M&P collectors like myself would give our eye teeth to add one to the collection.
By the way, these unusual revolvers were the subject of an article in a recent issue of the SWCA Journal. It was excellent reading, but even the research that went into that article failed to unveil the whole story behind this particular batch of revolvers. My own S prefix research has turned up a few parts of the puzzle. Over time, I hope more of the story will become known.
Once you get a letter on your gun, please share the results with us here on the Forum.