To convert a PPSh-41 to 9mm. you will need a magazine well adaptor to accept MP38/40 magazines, and, of course a Papasha 9mm, barrel. I.O. used to sell these conversion kits. They are not drop in no brainers.. Due to the variances in PPSh magwell tolerances, some fitting may be needed. The replacement 9mm. barrel also has to have a groove machined/ filed/ Dremeled in it to match the takedown pin and orient the feed ramp at 06:00.That's all that is needed. The Wehrmacht converted many captured 41's on the Eastern front in this manner. Years ago, I converted a Chinese Type 50 to fire 9mm. with an I.O. kit and it was a much more pleasant SMG to fire in 9mm.I still have a spare conversion kit if you are interested, but the only downside to this conversion is that MP40 magazines are rather pricey these days. http://www.ppsh41.com/ppsh2.html