If I could I'd give a thumbs up to Mike Irwin's posts beginning with number 27 that refers to Doug Sheldon's excellent book.
Just to back up a bit on the origins of the 38acp and the 38 Super (same round different loads).
In the late 1890's the U.S. Army began to look into semi-auto pistols to replace their revolvers chambered in 38 Colt. So Colt decided to build a gun to meet this demand. They worked with John Browning on the design.
Browning designed the 38 acp, a semi rimmed cartridge, and built a gun around it. The model 1900 which you can see on the link below.
http://www.coltautos.com/1900.htm
It sent a 130 gr. jacketed bullet about 1100 fps from it's 6" barrel.
It was tested by the Army and several versions were produced as a result of the trials. You can also see the versions at coltautos.com.
The Army was dragging it's heals on switching to a semi (debates were long and numerous) so Colt released commercial versions of the gun.
To make a longer and interesting story short the Army decided that they wanted a bigger caliber than 38. Browning worked up a 41 caliber variant of the gun and had a prototype when the Army decided it wanted a 45. caliber. Browning designed a cartridge for them the 45acp.
Colt and Browning had figured, by this time, that the parallel ruler design was too weak for more powerful loads than the 1100 fps. So the design was further altered, which led to the 1911 in 45acp.
Colt continued to make and sell the parallel link design guns in 38acp. By the 1920's though sales began to drop off. It then occurred to Colt to chamber the gun in the 1911 design. Thus the Colt Super 38 was born in 1928 chambered in 38acp.
The gun was widely marketed in 38acp as a hunting round and defense against dangerous game and as a gun for police (though it was never widely used as a police gun, revolvers ruled there, but it made inroads in the police market which worried S&W). It did sell well as a military round internationally.
Mike Irwin takes it from there as seen above. Eventually both the round (loaded more powerfully) and the guns began to be called the 38 Super.
The 38acp was built as a military round for the first semi the U.S. military adopted. That's it's origins and intent.
It's popularity forced S&W to develop the 38/44 Heavy Duty and later the .357 Magnum.