Smith 1 1/2
You have a very scarce variation of that model. There were actually 3 variants of the "short barrel". 2 1/2", 2 5/8" and 2 3/4". The late Frank Sellers wrote a book on this revolver. He with Roy Jinks (Smith and Wesson Factory historian) never found out why they made the 3 variations. Your's in the 2 1/2" bbl length is the least common found and worth the most. Oh, I just re-read your original post saying the barrel measures just a little more than 2 1/2"..It might be the 2 5/8" variation. Take a close look. I actually have the 2 3/4" bbl in my collection. Market value on these is respectable depending on condition. You should write Roy Jinks for a factory letter.I did for mine and ask him about production numbers. He would include that in the letter and you would of course increase the value of your Smitty accordingly.The Smith letters are pretty cheap too. Last one I got was $35.
BMur