A hearty Buckeye welcome from NE Ohio.
I believe that revolver was known (at the time it was built) as the Combat Masterpiece. In 1957, it became the Model 15. It was the 4” version of the Target Masterpiece, which was a 6”, target sighted, 38 S&W Special, K framed revolver.
A very nice revolver, I carried a Model 15 when I was in LE. Also used it in competition. They tend to be very good shooters.
Kevin