my advice is either take it to the local shop or Club, I recon it's one of 3 things.

1 you aren't tighting the nuts on the mounts enough.

2 your rifle don't like the pellets you are using, how well does it group? once re-zeroed? try a diffrentn pellet & see if there's a difference?

3 your crosshairs had it, the Scope might not be rated for springers & you have shot it too bits

either way if you go to a shop or Club they should see you right, thou I recon it US (Useless)

Hope it helps

Darren