Hubertus means maker and Buchesenmacher was the maker of this gun. Here is a little info from the net.
Cannot help you with a model number , as the PGH catered to special orders by the GDR export organisation and I have no catalog. PGH stands for Produktionsgenossenschaft des Handwerks = production cooperative of craftsmen, an early form of socialized companies in the GDR. The PGH Büchsenmacher = gunmakers was a coop consisting of the mshops, machines, stocks, emploiees and outworkers of the former I.Meffert, Suhl company. From his return in 1950 from soviet POW camps Georg Meffert tried to run the once family-owned company, but gave up in 1959 and fled to the West. On December 16, 1959 the PGH Büchsenmacher of 18 gunsmithes was founded. These were already pretty old men, in 1962 their avarage age was 68. In 1964 they had to stop making drillings because the specialized master had passed away. On April 26, 1972 the PGH was reorganized into the VEB Jagdwaffenwerk Hubertus, which in turn was amalgamated into the VEB Fahrzeug- und Jagdwaffenwerk Ernst Thälmann