The PP series (PP, PPK, PPK/s) are all straight blowback and can't handle the "full" 9X19mm round. The 9mmK (.380) is the only 9mm series cartridge they were chambered in. The other choices were .32 and .22LR. There was a 1930's 9X19mm prototype that looks like a big PP but it's not safe to shoot...if you have one you should sell it to me immediately...I am quite familiar with the 9mm vs. the .380/9mmkz. I know I remember seeing a PPK type pistol, made by Walther, in 9mm. I could be thinking of the P5 but I think it was before the P5 was around. I could be just spinning my wheels here.