After WW1, calibers (I use modern civilian designations to reduce confusion) 8 x 57 I and 8 x 57 IS – the latter being the military 7.9 mm – were considered “war material”. Ownership of rifles as well as ammunition was banned. The rimmed versions were not banned, by the way.
As a way to legalize existing weapons, cartridges 8 x 60 and 8 x 60 S were created around 1923. By reaming the chamber to the new length, an illegal “war” rifle could be turned into a legal sporter rifle.
Please note that the “S” identifier was introduced in Germany as late as 1939 to tell the 8.2 mm bullet cartridges (S) from the 8.1 mm bullet versions (no S).