AH! OK, I see the problem.
There were SOME early smokeless powders that were called bulk smokeless powders. These were a separate class of smokeless powder and were not the same as other smokeless powders like early Bullseye, Unique, Military Rifle (MR) 15. I have a list at home of early smokeless powders and their applications.
The bulk replacement smokless powders were, as I understand it, primarily aimed at the handloading market and not the commercial market.
As you note, these were intended to be used in the old black powder cartridges (primarily rifle, but they would also work just fine in handgun cartridges) without the need to measure.
These bulk replacement powders were also relative late comers into the early smokeless powder arena. I THINK, but I'll have to check, that most were introduced AFTER World War I.
The World War I era was a huge watershed in the American cartridge industry. Literally, in a matter of months, dozens, if not hundreds, of older cartridges were dropped from production as the factories geared up to supply European and US military contracts.
At the same time, production of black powder for the commercial market virtually ceased.
After the war, many of the plants didn't want to convert back to producing a propellant that was now seen as obsolete, so Du Pont developed the first bulk replacement powders.
These bulk powders kept with the new technology, were based on very slow burning smokeless powders that were used in artillery during the war (or so I understand) and required no costly line conversion back to what was seen as a dying black powder market.
The other factor that I've not discussed is that early smokeless powders had, generally, a very low energy content ratio, which required greater grain size. This is the factor that made rounds like the .44 Russian inefficient with the new smokless powders. You simply couldn't get enough of the early low energy smokeless powders in the case to make it perform like the .44 Russian.
A similar cartridge die off happened in the late 1930s, a combination of both the Depression and contracts that were let for World War II.
What's truly amazing, though, is that many of the cartridges that were, for decades either partially or completely obsolte, like the .38-55, the .45-70, the .45 Colt, the .45 S&W, the .32-20, and many others, have come screaming back to life.
Unfortunately, with the rebirth of many of these cartridges we had a similar situation -- lack of suitable powders. The old bulk replacement powders were discontinued in the 1950s/early 1960s. Hardly anyone shot the old rounds anymore.
But, with the resurgence in interest in American history that started with the centennial of the Civil War, the American Bicentennial, Little Big Horn, and the rise of Cowboy Action shooting, some of these cartridges are selling as well as they have in 100 years.
The .44 Special is a great case in point. Until Trail Boss came out a few years ago, there was no truly suitable powder that had both the burning rate and energy necessary to get standard ballistics but also to fill the case to promote ballistic conformity.
I used to load my .44 Special with WW 231, but it was imply unsuitable. A tiny tiny amount of powder in a huge case. Trail Boss changed that.
I've said it here numerous times. Trail Boss has characteristics that are, from my understanding, VERY similar to some of the later bulk smokeless replacement powders. It's not a truly bulk powder, but it's god awful close.
"The "other story" that I heard was that the .44 Special was intended to be more powerful than the .44 Russian, and was intended to maintain that margin when it was reloaded with black powder by handloaders, back when smokeless was not available to them."
Well, I'm not really sure that's the case. The .44 Special was a late development, 1907. Original published ballistics for the .44 Special, whether with black powder or smokeless, were identical to the .44 Russian.
The .38 Special has a different story behind it altogether, but one that is equally as interesting.
Final note.
There were three cartridges, all introduced in roughly the same time frame, that used the name Special -- the .38 and .44 Smith & Wesson Specials, and the .32 Winchester Special.
In the case of the two handgun rounds, both were offered commercially from the beginning in both black powder and smokeless loads.
The .32 Win. Special was only offered commercially as a smokeless round, but it was intended to be reloaded with either smokless OR blackpowder at the owner's choosing.
