To avoid further confusion on Colt serial numbers:
Prior to 1949, .38 caliber Officers Model target revolvers were serial numbered with the base model of the day; that is, the New Army/Navy, Army Special and Official Police. From 1949 through 1952, the .38 caliber Officers Model Specials were numbered in a uniquely assigned range identified as Officers Model Special in the Proofhouse charts. Starting in 1953, the .38 caliber Officers Model Match (OMM) was serial numbered with the Troopers.

In short, the .38 Special Colt Officers Model Target, third issue (OMT, the subject here) was serial numbered in the Colt Official Police series from 1927 to 1949. The .22 OMT is numbered in a different series. There were some OMTs made in .32 S&W Long (Colt New Police) during the pre-WWII period, but not many. I have no idea how they were serial numbered.