That is an unusual loading. At least, it is for me. I confess that I don't get the reason for it.
Aluk, i trust that you won't feel that discussing a final point here isn't a "derail" to your thread topic--there is some limited relevance here.
i've found that the various pipsqueak .380 pistols work fairly well with standard pressure ammo--but can indeed produce some over penetration. to mitigate the over penetration, the self defense ammunition has been offered in hotter loadings. though not a frequent occurance, in some cases i've found that this can interfere with proper slide function. in addition, they are also more difficult to control, and can be tough on these pipsqueak rigs.
as a potential alternative, a small revolver can be handy and more forgiving, as there are no slide functioning issues to contend with when utilizing the hotter loads.
(the reason for the 9mm pill in the load):
in the mid 1980's, i bought a new S&W model 60.
the first function of that rig was dispatching wounded coyotes. i used a 158 grain hardcast pill for that task--shooting those yippers in the head.
the second function was for home protection. in those days, unless it was a special case, folks did not have concealed carry permits in our state--so a potential self defense situation with a smaller rig like this was more likely to occur in the home, and possibly even more likely to occur in the bedroom. thus it's second role was that of a "night stand revolver."
in my opinion and experience, the loads i tried back then in the mid to late 1980's gave too little upset, and too much penetration, due to the lower velocity of the very short barrel. subsequently, i tried handloading the 110 grain Sierra Blitz, but in testing that pill, it did not expand very well either, even when i tried a few at +P loadings. therefore, i went to trying the lightweight 9mm pills such as the 88 grain Speer, and the 90 grain Sierra HP. they worked very well in that there was no over penetration, but expansion was to the point of significant fragmentation. a few years later the 90 grain Gold Dot pill offered both desired attributes--good expansion, and no over penetration.
the over penetration was a significant concern to me, as our son's bedroom was right across the wall, and the only real separation between the two rooms was two pieces of 5/8 thick sheetrock, and a 3 1/2 inch dead air space. in a self defense situation in the middle of the night, this type of arrangement makes potential over penetration of significant, grave concern to any responsible gun owner.
thus the purpose for that "unusual load" back then, which isn't really altogether new--others were doing something similar too (before the mid 1980's, Smith and Wesson even offered their .357 magnum 90 grain soft point factory load--if i recall, they were known to be aggressive in penetration).
the .357 load i posted earlier is just an "amped up version" of the .38 special loading that the model 60 was loaded with on the nightstand.
as mentioned earlier, modern factory offerings make this sort of thing nearly obsolete today...
for some folks, the smaller, lightweight snub .38 revolver can be a possible alternative to the tiny .380 auto pistols of today--although the size/weight of those popular, tiny .380's is near impossible to better for everyday convenient carry...
