I have a 2007 S400 which came from the original owner with AA Diabolo Field headsize .452. Despite their age, they seem to be in perfect condition and the rifle likes them. Much to my chagrin, another member of the local club asked to try it and rang the bell target at 30 yds with three consecutive shots! It took me a while to find the target...
This larger, but popular, headsize fits nicely in the breech and you can just feel it pop past the seal as you close the bolt.
Took the old girl back to the range yesterday. Bit windy but can't waste a rest day. The Range Officer also had no problem ringing the bell with it. I must get some practice in!
Rob.