I feel i’ve a prewar Smith and Wesson 1899 first mannequin navy and police. Or is that this a more recent .38 revolver? Maybe a mannequin 10? : weapons

I’ve had this revolver for just a few years, I purchased it from a pawn store who informed me it was a retired cop’s gun. They did not appear to showing interest and could not inform me something any it different then being a .38 particular revolver. I made a decision I needed to be taught extra and my gun and I feel i’ve a S&W 1899 first mannequin M&P revolver. Any assistance on figuring out can be appreciated.