Hello and welcome to the forum. What you have is a Model 67 .38 special revolver. It is the stainless version of the Model 15, which was available in either blue or nickel finish. Someone else will come along and provide you with a year of manufacture and a probable value range. As you indicated the rear sight is adjustable for windage and elevation. The larger screws you describe are used to make these adjustments. They are a wonderful revolver and one of Smith & Wesson's mainstays. Enjoy your new toy and when you get a chance, post some pics. We LUV pics!!