This is a label for 7.9x57 German MG ammo made by the Czechs under German occupation. Aside from the bullet jacket plating metal it is the same as any other German MG ammo of this caliber. Why bother with a special designation ?
It seems that anyone who actually cared could tell by the maker code that it was Czech made so why bother with the sS(t) ?
Would it work better in the Czech made guns ?