Bohler Blitz Stahl are most likely the gunsmiths Name or the Name of the Company who made the gun.
It may be an small Family gun shop/builder (maybe as others said in Fehrlach Austria). It maybe as well in the case of a guild that the gunsmiths Mr. Bohler, Mr. Blitz and Mr. Stahl made the gun.
Bohler at least in german is a Family Name (surname) as well as is Blitz (means in english "ligthening"; like Blitzkrieg) and Stahl is a common german surname meaning simply "steel".
If your motherthongue is english it is easy for you to figure out what a word means in german since both languages are similar. To learn english on the other Hand you better know previously german and spanish since modern english is in a way a mix of latin (spanish. Normans spoke French and when they conquered England latin words entered the anglo saxon/old german language) and german (anglo saxon. Wessex, Sussex, Essex).