It strikes me from thread 3 that your rifle isn't so much out of zero but inaccurate as alluded to by Muffer. When we release them from workshops we test them for accuracy and NOT zeroing - although it's fair to say that they're sort-of zeroed*. I think that it's the accuracy pattern that you need to concentrate on correcting.
* Anyone who has seen a sniper rifle returned from workshops or issued from new will have a note attached to the paperwork that states words to the effect 'SNIPER RIFLE; NOT ZEROED (or unzeroed?) FINAL ZEROING IS THE RESPONSIBILITY OF THE END USER'