I don't believe so.

There are many (myself included) who accept the convention that a 6" barrel length with target sights is the standard for a target grade revolver and so it was appropriately named the "Masterpiece" . . . anything less than 6" is considered a "Combat Masterpiece". I believe that is the factory nomenclature used since the introduction of the 4" in 1949.

The 5" was not a standard (catalogued) item in 1952 when the MSHP special-ordered theirs (nor has it ever been to my knowledge) so, as Shawn explained, a group of 6" Masterpiece barrels were modified by cutting the barrel and replacing the Patridge front target sight with a Baughman ramp. It's easy to see how this group of revolvers could be referred to as Masterpieces that were simply modified to the customer's specs . . . rather than their Combat Masterpiece name.

Russ