Thanks for bringing this 'Koh-I-Noor' to my attention again ole' Chief. I was pretty last time I had a peekaboo.
Herr Weber, I regret to inform you, but the folks who could shed more light on this craftsmans firm died 2 to 4 decades ago.
Happily, this riddle can be solved through simple translation. Established in 1901, warehouse and distributorship of arms and ammunition with their own target range, numer 6429/6430 is obviously of Belgian manufacture. Ah, that naggin Fabryka Broni (arms factory) yes but like Otto Bock of Berlin, or Griffin & Howe of NY.
Congratulations on your ownership of a wonderful custom by Jaruszewski doppelflinte luxus from Liege Belgique in Silesian, Thuringian, or Poznanski style.