its common to find the makers name stamp into the break action frame like here in my own 16 ga double gun "Gebr. Adamy", one of the gunmaker still exist.

the Bühag gunmaker were got the blank parts like barrels or the actions from the Jagdwaffenwerk and build the gun traditional by hand. technical they are more or less the same like the models made by the jagdwaffenwerk. an uncle have a 8x57IRS o/u Bühag double rifle with sidelocks thats the same like a Merkel 323e.
but there also some special made things like the Vierling on egun last week.