Welcome to the forums from the Wiregrass, Steve! It's a .38 Military & Police revolver, post WWII. It is an ancestor of the Model 10 which technically began in 1899 but received numerous engineering changes from that year until the Model 10 was launched in 1958. Jim is correct that it is the model just previous to the pre-Model 10 which was launched in 1948. Of course, S&W didn't call it that. To them it was the .38 M&P.