The Chiefs Special target was the now discontinued Model 50, with a two or 3 inch barrel, blued steel and adjustable sights. In 1990 S&W made a run of target sight, three inch barrel Model 60-4s.
PS229s gun is one of these. Whether S&W actually called it a Chiefs Special Target is another matter.
But, as mentioned above, CTG has been the abbreviation for Cartridge for over 100 years.