Darn Bob you did it again, never heard of those dash numbers before.
Prior to the new system of model numbers put in effect around 1957, the model number was used primarily among factory and distributors. The system consisted of the frame (I,J,K, or N, there being no L at the time) followed by the bore diameter, i.e. 357, 430, 451, etc. The letter T suffix added for target sighted guns.
Problem arose with the .38-44 Outdoorsman and the .357 Magnum, both of which were N-357T. Same as a with the 1955 .44 Target and the.44 Magnum, both N-430T model numbers.