... I will argue that better prices can often be found online and if the buyer is aware of what is for sale, asks questions, requests additional photos, you will get what you want for less than gun shops more often than not.
Supica/Nahas actually show lessor condition Combat Masterpiece revolvers with lower value than comparable 6" guns. My guess is that demand for K22 short barreled guns is less than 6" guns, since the main purpose of this model is target shooting. As for more 5 screw Masterpiece revolvers than Combat Masterpiece revolvers, the 6" model started in 1946 while 4" model did not start until 1949. Also, it is surmised by some that there are less 4" CMs out there because demand was less than the Masterpiece revolvers throughout CMs production run.