Looks like I see a Sauer & Sohn stamp or two, so they either applied some effort on the Blitz lock dreiling or were sourced from components. Also the tubes were sourced from Carl Gottieb Hnel or one of its subcontractors, Gebhard Helmuthhauser / Gebhard Helmuthuser.

13 gramme / 200 grain bullets are quite easy to source. The 13 gramme bullet & 88-8 point to the smaller diameter on the 8X57R/360?

Cheers,

Raimey
rse