is it a .38 spl? Looks like an M&P. Apologies if I'm being direct, but I wouldn't consider that "great shape". I'm only saying that in case you're looking for it's value.
It is a .38 special. It's probably been untouched in a box for 50 years or more and could use some tlc. Haven't even tried to clean it yet. Just wondering what year and model it may be.
Welcome! It's a .38 Military & Police from about 1921.
Artificial light sometimes makes a worn blue finish look like rust, but if it really is rusty using gun oil and a rag will help remove it. Soaking it in 50:50 acetone and ATF for a week (sealed container) also works. Flushing out the internals with brake cleaner with the stock panels removed and relubricating is probably also a good idea.
Twalls, Welcome to the forums from the Wiregrass! Are you sure about that serial number. I see a Model 1902 M&P. It has the old flat spring action so it was made before 1905. If the serial is 5 digit, 363xx, that would put it in 1903 or so.
^^What Murphydog said!! Automatic transmission fluid is great stuff. The acetone or mineral spirits things it out to penetrate better Make sure the grips are removed or the acetone/atf will damage them. That gun may clean up nice and work great.