22ppc
Since you did ask about 100-200 yard Benchrest, I will give you an answer with that in mind.
The fullsize 22PPC is not that competitive, mainly because it (probably) passes that magic powder volume to bullet diameter that seems tomake chamberings such as the 6PPC, 30BR and a few others so inherantly accurate.
Many have tried the full size 22PPC. It simply leaves too much on the table, agg wise.
Of course, when you shorten the case .100, all sorts of magic occurs. It becomes one of the most accurate chamberings ever conseived. As was said, the 220 Russian does about the same thing.
In my opinion,the three most inherantly accurate chamberings at this time are the 22PPC .100 short, the 6PPC, and the 30BR........jackie