lazy
Hey, I'll toss some stuff out there.
As noted, the .38 spl started as a revolver cartridge, I'll add, with black powder, pre 1900. I think S&W is the firm that introduced it. Later, loaded with modern smokeless powder and various bullets, it went on to become a favorite, especially with the US police, until the 1990's, likely later in places. It is a rimmed cartridge, the rim locating the cartridge in the revolver cylinder/chamber. In its most modern renditions, it appeared with the designations .38 spl +P and +P+, denoting higher pressures and velocities.
The .38 Super, also seen as the Super .38, is an auto pistol cartridge seeing life about 30 yrs later in 1929. The Super .38 was in improvement on a previous .38 caliber auto pistol cartridge of modest power. The Super was introduced by Colt, for the 1911 pistol and has always been loaded with modern, smokeless powder. It is technically, I believe, semi-rimmed, which gave some issues, but is resolved with modern varieties. Initially, it had some favor with LE apparently, due to its increased penetration over the .45 acp with ball ammo. It also had less recoil and a higher mag capacity in the 1911 over its .45acp version. Eclipsed by the .357 magnum, it remained in the shadows until modern competition discovered that a hot .38 Super (.38 Super +P) could reach certain power leves in shooting sports popoular at the time, (1980's-90's) and provide additional capacity over the .45, largely favored previously in those competitions.
I believe The Super suffered another heavy blow when the 9mm began to appear in +P and +P+ versions, largely equaling the velocity advantage of the hot .38 Super, in a larger variety of pistols. Sig made some Supers in the P220, about all others I can think of were 1911's and their clones. It remains a niche cartridge here in the US. I read it has some popularity in nations where military cartridges like the 9mm and .45acp are prohibited for civilians, South America for example (not a nation, granted).
