ANY BODY USING THESE
I am having a very similar problem with my CZ. The reason I have said nothing is because I shoot so badly. However, I am also starting to think that it may be caused by the change in weather.
Cold air is heavier than hot air and therefore as the temperature drops so the volume of air increases. This would in turn increase the friction on the pellet and change the POI. Also the o-rings may be less pliable and therefore not sealing as efficiently. The reason I say this is because the first few shots even worse than me and then after 3 or 4 rounds they begin to group fairly well.
But this is just my thoughts