Wunder & Gunther
This pistol was retailed by Wunder & Gunther, Universitätsstr. 1, Leipzig, a gunshop that existed from 1878 to 1910.
Such "Kunstschützenpistolen" = sharpshooter pistols were manufactured by several shops in Zella–Mehlis for trade, a sort of cottage industry.
Obtaining additional markings could indicate the true manufacturer.
The service load data 1.8 grams = 28 grams of lead bullet in front of 0.2 grams
= 3 grams of black powder points to the short .22 cartridge.