Noticed this one for sale in Switzerland and it dates from the same year that the K31 was first issued.
A total of 18.209 of this type of revolvers were issued to the Swiss military from February 1933 on at a price of 90 francs per gun, the last one was made February 1946. The serial numbers are similar to the 06/29 Parabellum pistols and start at # 50.000, it also had the same three grip color varieties, at first red, then brown and at the end black.
Guisan.
