In 1927, a Berlin resident named Richard Kulisch patented a .22 rimfire conversion kit for the Luger pistol. Kulisch’s conversion used a magazine and fired semiautomatically, which made it a much more practical conversion for military and police training than the 4mm single shot conversions than in use. Kulisch appears to have sold the rights to his design to the Erma company - they were an ideal company to market such a thing, having previously sold a .22 rimfire conversion for the Gewehr 98 rifle to the German military. They proceeded to do the same thing with the Luger conversion, which was tested by the military in 1931 and adopted in 1932. It would remain in production until 1940 for the military and police, although it was not really made in large numbers.In addition to this military contract, Erma made a version for the Swiss commercial market, which was sold by a Zurich gunsmith named W. Glaser. The kit turned the Luger into a simple blowback pistol, and is quite a clever design. In the 1950s, Erma would begin production again for the American commercial market, with a few changes. These were sold by Interarmco, and packaged in a distinctive green box.