I did briefly chat to Sven yesterday to get more info and he said that there is no power limit to the rifles that may be used. Targets will be set up between 10 and 40m with a few out to 60 - 70m for the guys with the more powerful rifles. Most targets are kept relatively close so that the 12 and sub 12 fpe rifles can still knock them over. Target distances will be unknown so the shooter needs to calculate the distance themselves. No rangefinders allowed.
Just to be clear, I have no involvement in organizing or hosting this event, I am simply sharing it. Any queries should be directed to Sven via the number provided above.