It is a .357 mag S/N S83XXX. I'm not sure what model it is. Any info would be great.
Your .357 Magnum was manufactured in 1951-52, and the model is simply the same as the caliber " The .357 Magnum." This is the gun that became the Model 27 when S&W began assigning model numbers in approximately 1957. Your gun is known as a "5-screw" because there are 4 screws holding on the side plate (one hidden under the left-hand grip) and an additional screw in front of the trigger guard. Model 27s and (especially) the pre-model .357 Magnums are somewhat sought after - if it's in good condition you have a very special gun there.