The 6mm PPC is an outgrowth of the .22 PPC and based on the same case configuration with the neck expanded to take 6mm (.243") bullets. This cartridge was also developed by Dr. Louis Palmisano and Ferris Pindell and based on the 220 Russian case, which is a variation of the 7.62 x 39mm (M43) Soviet military cartridge. Cronograph tests by various individuals have demonstrated that the 6mm PPC gives very uniform velocity readings, which accounts for its fine accuracy. On the other hand, practically all rifles chambered for the cartridge are heavy accuracy jobs, and that must also be a factor. Rifles for match shooting usually have a 1 in 14 inch twist, although a few are turned out with a 1 in 12 twist. The 6mm PPC is not only an outstanding benchrest cartridge, but gives very good results on small game and varmints. It is only slightly less powerful than the .243 Winchester despite the much smaller case. It should also do well on deer and antelope at moderate ranges. The velocity with the 90 grain bullet is only some 100 to 150 fps less than the .243 Winchester. Popularity of this caliber is growing beyond benchrest shooting; varmint hunters are now taking it up as well. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.