well I must say that your the only person that I have even come across with such a problem with a CZ 452
if I didn't know better I would suggest that it was the operator and not the gun.
However I will suggest that you contact CZ-America as something is clearly not right. Here in the UK the CZ 452 is about
THE most common rimfire rifle in use especially for Rabbiting. The only comment I hear is that the triggers can be gritty but that's an easy fix
Now back to the CCI ammo............... sorry but the Mini Mags are just not that accurate. In the club I belonged to before moving we had a annual .22 LR competition shot at 200 yards and the idiots would go and buy Mini Mags thinking it would help them due to the hyper velocity however every time they were beaten by someone shooting std velocity ammo. I found it quite amusing especially when it was won one year by a M1 carbine .22 LR copy/clone shooting std ammo but usually it would be a BSA Martini which won it usign std velocity ammo.