I know the above said gun was made in 1948, known as the Combat Masterpiece. I know it didn't become widely used until around the 70s when it and other adjustable sight revolvers became more widely accepted. I "hear" the FBI had a part in it's development. It appears sturdier than the M-10 tapered barrel as it seems to have a thicker and heavier barrel (though not as thick as the bull barrel of the M-19 and later Heavy Barrel M10). It's earliest design actually looks like some custom work done by Ed McGivern on the Military & Police (pre model 10)

Anymore history. More about the FBI's involvement (I understand J. Edgar Hoover took on a lot of McGivern's techniques and ideas)

The Combat Masterpiece was developed during 1949 and did not appear as a cataloged item until 1950. As far as any direct FBI involvement (or J. Edgar Hoover himself) I know of nothing in the record to indicate this. Certainly, it was an FBI agent named Baughman who helped design the type of front sight that was used on the Combat Masterpiece, but that's about it.
As far as its use blossoming only in the 1970s, that simply is not true. For one thing, the U.S. Air Force started buying large quantities of them at least a decade before that. I carried one during both my tours in SE Asia.
Moreover, LEOs were using them and the Combat Magnum (also a target sight gun) long before the 1970s.

__________________
Jack
SWCA #2475, SWHF #318

Here's a former LEO Combat Masterpiece that was shipped along with 364 others like it to the Missouri State Highway Patrol in 1952. It is unusual in that it has a special-order 5" barrel.

__________________
Jack
SWCA #2475, SWHF #318

Allegedly, the impetus for a 4" combat version of the Masterpiece originated with Evaluators, Ltd., which catered extensively to military personnel. Evaluators Ltd. I don't believe that there is much, if any, connection to the FBI.

The story I heard is that Hoovers FBI agents were practicing one day with 6 in target masterpieces. They liked them so much that hoover or his agents requested S&W build such a gun for duty and/or plainclothes carry with shorter barrel. The result was the M15