The U-94 "Udar" (Strike or Blow in Russian) revolver was developed during early 1990s at the famous KBP design bureau in Tula, Russia. It was intended primary for police use as a concealed carry weapon with enhanced effectiveness against a variety of targets, by developing a variety of 12.3mm rounds with various bullets (lead bullets for maximum stopping power, hardened steel AP bullets for maximum penetration against barriers such as doors or car bodies etc). The rimmed ammunition was based on shortened 32 gauge brass shotgun shells, cut to necessary length. For various reasons the police version didn't caught on with Russian law enforcement, and a reduced power version, known as U-94S "Udar-S" was developed for private security companies. It used shorter cartridges with lead bullets only (no AP).
U-94 "Udar" revolver is a conventional double-action revolver with semi-exposed hammer (hammer head is accessible through the opening at the top rear of the frame for manual cocking or decocking) and side-opening cylinder that holds 5 rounds. Cylinder opens to the left, spent cartridges are ejected all at once when ejector rod is pressed, fresh rounds are loaded one after another manually. Revolver has unusual appearance as it was optimized for concealed carry and short-range use only. It had a steel frame and cylinder, and polymer grips.