Here is a .44 HE Fourth Model of 1950 Target (also referred to as a pre 24) with a barrel length of 4”. This gun shipped to Olympic Wholesale in Los Angeles, CA in January 1955. The letter from Roy Jinks states it was equipped with the red ramp front sight, and the “bright blue finish”.
The letter also states the 1950 Target Model was only catalogued as being manufactured in blue with the 6˝” barrel, however S&W did make limited quantities in 4”, 5” and 5˝”. It is mentioned in SCSW that the 4” version is “scarce”.