I have checked & checked the scope height even done the measurment shooting at 30cm with the end of the scope covered with foil & the small hole, I believe this is how you correctly set the scope height in chairgun.
I have two mates with the same scope on different guns & there's are virtually the same as chairguns settings. Granted the best way to set this up is actually shooting at different ranges but that's my point software should allow us to do this with some margin of error without having 55 yards to shoot, so it must be the scopes turret. What else can it be?
Thanks for your comments, can't wait to sort this out & understand what's going on.