Excuse the newbie question but do you find that your rifles zero always moves when you fit a moderator?
I've just fitted an Ase Utra North star NS-3s to my Browning A bolt 6.5x55 and found the zero altered at least 2" low and 1" left compared to no moderator fitted, this was at 25m (only range available at club today). After thinking about this on the way home from the club I came to the conclusion that it's due to the weight of the moderator on the end of the barrel as the North star is quite hefty (660-700g). Also I've not had the chance to set the rifle/scope/zero up for me as only just got the rifle, hopefully get chance to get on a 100m range in new year.
Was shooting Privi 139gn target rounds if it makes a difference.