The story I read about the 220 Russian was, the Russians had used it for several years in rifle competitions, the cartridge being based off of their 7.62X39 case. The Americanized versions, 22PPC and 6PPC came about from a primer study by Ferris Pindell. The Russian case was chosen as the basis for the PPC cartridge because the flame size and pattern from the Federal small rifle match primer matched the internal configuration of this case.