This is a S&W that I have always wanted since the first time I saw one. It's a M&P Pre-model 10 with a 2" barrel, square butt. It left S&W's factory in October of 1946.
I was given one by my grandfather when he departed this earth. His was bought in 1964. It has been shot 5 times right after he bought it. Still has the original box and paper work. These are nice pistols. Yours looks real good.