Ljubodrag,
Szailer was one of the largest gun houses in Vienna. They also sold mail order all over Austro-Hungarian empire and published nice catalogs for this purpose. Most of their gund were of Belgian, German and Austrian origin; they also offered some US repeaters. I once owned a Szailer hammer drilling in cal. 500 Express (Short)that I found in Croatia and was told it was owned by count Draskovic and later used by Tito's partisans in the uprising of 1941. The company was established in or about 1866 and was doing well till WWI but I'm not sure what happened to it afterwards. I don't have any idea where their records might be but would start a search by writing to some institution in Vienna such as State or City Archives or maybe the Military Historical Museum (HGM). An email to Dorotheum Wien could also bring some information, they sell old Szailer guns from time to time and should know something about them. Good luck.
Pozdrav u Srbiju,
Jani
