What have you guys achieved with this caliber?

Gosh, I've achieved lots of things. I've one some benchrest matches with a 6PPC, killed some deer and turkey, etc.

Do you have a more specific question?

well, accuracy, energyies, velocities and shooting at largerish stuff like roe deer?(20 - 23gk(48lb)

Express, a roe deer is a piece of cake with a PPC. A well built rifle will be more accurate than you are. You will achieve about 3100 fps with 75 gr. X-bullets, or 2900 with 85 gr. Partitions (both require 12 twists). HTH, Dutch.