It's a .38 Military & Police 4th change.It has serial #s 2780xx
Please post pictures so we can evaluate its originality. The bluing on S&Ws from this era was beautiful when it was new, but it seems to have been more fragile than the bluing used on postwar guns. Most prewar S&W .38 M&Ps I've seen with decent-looking bluing have been refinished at some point, which ruins the collector value of the gun.It's in pretty good shape. Blued, not nickel plated and very little wear