Current Rifle Cartridges
    6mm PPC USA obsolete
The 6mm PPC, not the 6mm PPC USA was developed by Dr. Louis Palmisano and Ferris Pindell which is why PPC, stands for
Palmisano, Pindell, Cartridge. The 6mm PPC USA is the "King" in short-range benchrest competition, and some people will  say
“the most accurate cartridge ever invented”. It is basically unavailable and obsolete today.
As a Wildcat Cartridge (for benchrest use) from the 220 Russian case, which is a variation of the 7.62 x 39mm (M43) Soviet military
cartridge. Then Sako of Finland began turning out commercial bolt action rifles and supplying loaded ammunition late in 1987, which
turned the definition of the Wildcat Cartridge into a proprietary cartridge, to my knowledge SAKO no longer makes this caliber.
The 6mm PPC-USA will not work in the 6mm PPC (Benchrest) Rifle as the 6mm PPC USA has a 1.503" length  case and the
6mm PPC has a case length case on 1.452".