Try this website:
http://www.gunshop.com/
Krupp Stahl = Krupp Steel, Krupp has a long history of arms making, probably produced the steel the barrels were struck from. Hirschberg may be where the gun was built and A Haelbit might be the builder.
Many Drillings were built by "Guilds". Independent master craftsmen who specialized in a specific gun making art IE barrel making, stockmaking, fitting actions etc. "Guild Guns" were often put together by a series of craftsmen for a "Builder" who then sold the guns to gun dealers or importers.