Okay, found the problem. The Hawkesbury River projectiles with 0.458 diameter are too small to work in my CZ. I bought some Westcasting projectiles which are 0.459 dia and tried them at the range today, and they worked. Accuracy wasn't real flash but I can work on that - part of that was due to aiming errors since they shoot a foot high at 50m. I had to aim below the target - should've used a bigger target. I'm going to put a scope on it for next time.

Trailboss loads did about 6 MOA while AR2205 did 5 MOA with 4 of the 5 shots in 2 1/2 MOA. Horizontal dispersion was minimal. Most of the group size was in vertical dispersion thanks to the sighting issues. Anyway I only tried 5 of each, so there is plenty of fine tuning to do. I'll probably stick with the AR2205 since this puts it near the velocity range I am targeting (approx 1700fps).

The pigs had better start getting nervous, these loads are going hunting with me next time.