Hello!
ROS 1945 dated magazinetaschen are very very hard to come by, ros is the latter october-december code for bla which is Ernst Gustav Leuner in Bautzen. There were two factories located in the same area, the other one was named Johanes Leuner Lederfabrik. In 1946 the factories were expropriated and forced to produce leather goods for the red army, in the sowjetische bezatzungszone. I assume that Leuner was one of the latest to earn a contract on g43/k43 pouches. Note that your pouch has a single rivet on the front flap.