Otto Eberhardt Patronenfabrik

Otto Eberhardt Patronenfabrik (English: "Otto Eberhardt Cartridge Factory") was a Nazi Germany munitions company. The company's Hirtenberger Patronen, Zündhütchen und Metallwarenfabrik (English: "cartridge, primer and metal fabrication in Hirtenberg") near Wiener Neustadt (proofmark "am") used forced labor from a sub-camp of the World War II Mauthausen-Gusen concentration camp and produced ammunition including 9×19mm Parabellum (pistol and submachine gun) and 8 mm Mauser (rifle) cartridges. The company also had a factory in Ronsdorf near Wuppertal (proofmark "ap") which produced rifles. Additional Gustloff facilities were in Meiningen and Weimar.

Hirtenberg aircraft
Otto Eberhardt Patronenfabrik also purchased the assets of the Hopfner aircraft company and had continued production of both de Havilland- and Siemens-powered aircraft under the Hirtenberg brand.