Here is a 7.92×57mm Mauser manufactured in Guangxi Arsenal (originally was located in Liuzhou, Guangxi Province, then moved to Chongqing in 1940 due to Japanese invasion). The jacket of its projectile is cupronickel plated steel.
The headstamp of it is ”卅三 十一” and a symbol with an X in a circle. “卅三 十一” means “thirty-three eleven”, indicating that it was manufactured in November, the 33rd year of the Republic of China (1944). The symbol exactly represents Guangxi Arsenal.
What’s more, the machines Guangxi Arsenal used were imported from the famous German arsenal, Polte. Maybe that could explain why it used an sS type projectile while the most of other Chinese 7.92 Mauser at that time used S type projectiles.