What started to emerge after a year of their work, was a truly remarkable gun, with many novel and unconventional design features. The Rak was a selective fire weapon, yet the trigger had no selector lever of any kind. It fired semi-automatically when squeezed lightly, and full-automatically, if squeezed all the way back. This was pioneered as early as 1920s in the Arsenal Tallin SMG (1924), then the idea was taken over (though of fundamentally different design) in the early 1930s by the designer(s?) of the Bergmann submachine gun . The Polish design is again radically different from both Tallin, Bergmann and Czech Sa-23/26, using only the general idea of progressive trigger. Soon, in 1969 the Austrian Steyr MPi-69 joined the progressive trigger selective-fire club, but the feature still remained unique and deep-niche, until in 1977 the space-age Steyr AUG rifle made it a household idea.