slicksleeve:
Model 28-2 Highway Patrolman dates to 1968 0r 1969. Serial range for those years was S305000 to S329999, so 1969 is more likely.
Model 57 .41 Magnum Target was manufactured in 1979 or 1980, with 1979 more likely.
Model 657-2 .41 Magnum Target Stainless dates to 19890r 1990. The serial number dates to 1989, but the 657-2 variant was first offered in 1990. My guess is a 1989 build or shipping in 1990.
kain00:
If the number you are quoting is from under the cylinder yoke/crane, then it may not be the serial number. The serial number is always found on the bottom edge of the grip frame, it is sometimes duplicated under the cylinder yoke.
That said, if the serial number is 616xx then it could be one of two guns.
Option 1: .38 Military & Police Model of 1902, 1st Change. This is a medium or K Frame gun, with a round, not square butt. The barrel should be marked '.38 S&W Special CTG & U.S. Service CTG'. The extractor rod is exposed.
These guns lack a positive hammer block safety and should be treated as 5 shooters, with the hammer down on an empty chamber. They predate heat treatment of cylinders and I recommend they only be shot with standard pressure lead loads, no jacketed or +P marked ammo.
Option 2: .38/44 Heavy Duty (Pre-War). This was a .38 caliber handgun using the .44 sized large 'N Frame', hence .38/44. These guns were intended to shoot a high velocity load and any commercial standard pressure or +P load should be safe to shoot in it. As with the Military & Police it lacks a positive hammer btlock safety. The cylinder is heat treated. Shrouded ejector rod. Barrel stamped .38 S&W Special CTG on the right side, Smith & Wesson on the left and patent dates on the top. Collectable. Falls into the period 1935 to 1943. Serial range 43954 to 62335. My guess is it shipped in 1939 or early 1940, before war production began.