As Murphydog stated it is a "K-22 Combat Masterpiece" which was introduced around 1950 as a new model,
some people refer to it as a "Pre Model 18" since it became the Model 18 around 1957-58 when model numbers were introduced.
The 5 screw frame and "High Speed hammer" were used until around 1956,
The satin blue finish changed to bright blue around 1954,
The shoulder on diamond Magn grips changed to the tapered style around 1953,
If the number stamped inside your guns right grip panel matches the serial on the guns heel my guess is your gun is a 1953-1954, If you post the serial can confirm and narrow it down a bit.