I have a six shot, K frame .38 with 4" barrel, adjustable sight, it looks like a model 15 but isn't stamped such. S/N is K191803 is stamped on the butt. Any help would be appreciated in ID'ing the gun and age.
That serial number is from around 1953. Model numbers weren't assigned by S&W until 1957. You have a Combat Masterpiece, sometimes called a pre Model 15.
I have a 15-6 that was a police or security firm turn in. It was also quite holster worn on the outside, some discoloration in the bluing but no pits, and with chips and bruises on the grips. The barrel and chambers were in excellent condition and has the best trigger pull in both single and double action of all my Smiths. I bet yours is a very nice revolver that was carried a lot and not shot much. Enjoy it for what it is.