7,9x57 Hulse for S-Patrone


Please, help me to understand the situation with brass cases for S-Patrone in time of WWI.

According to Brandt, Hamann, Dr. Windisch. DIE MILITÄRPATRONEN KALIBER 7,9MM IHRE VORLÄUFER UND ABARTEN. 1981, there where only two types brass cases for S-Patrone:

S-Hulse made from brass 72/28
S67-Hulse made from brass 67/33

These types had also slightly dufferent inner constructuion (exactly - the constraction of case base partition), may be because the brass 67/33 was more hard then brass 72/28.

But after sectioning the case with segment lines in headstamp I found that it’s construction also differ from previous models. Brandt, Hamann, Dr. Windisch written that this case is a same as S67-Hulse and had segment lines only to identify cartridges with cannelured bullets.

I think that this segmented case was a third type of S-cases used in WWI. May be it was developed for MG or may be it was something like Einheitshülse 88.

Did somebody know the official designation and destination of this case?