Pretty easy. That is a Rast & Gasser revolver. Adopted as a service revolver by the Austro-Hungarian Empire in 1898, they remained in service with police and reserves up to the end of WWII. They were also sold on the civilian market, and the grip on the one shown would indicate it probably was some special piece rather than a common military gun.
They are actually a very good revolver though, like most European service revolvers of the day, underpowered by modern standards. The straight grip looks odd, but is really quite good in double action firing.
The caliber is 8mm Rast & Gasser (8.1x27 and Revolver Cartridge, Model 1898 are other designations). It is longer than the .32 S&W Long, but the latter will work fine in the Rast & Gasser.
Since you appear to be working from pictures, you may not be seeing the left front of the sideplate but they are usually marked "PATENT/RAST & GASSER/WIEN" [Vienna].
An earlier model with the same takedown, well shown in your pictures, was the inspiration for the Japanese Type 26 (1893) revolver. It is one of the few revolvers that can be almost completely disassembled without tools of any kind. Many are damaged at the front of the frame by people trying to pry up the sideplate without first unlatching the trigger guard at the rear and pulling it down.
Jim