With most muzzy loads (especially sabot rounds) I have almost always found it better to sight in at 100 yards, then go back to 50 yards to see where you are hitting. Many of my loads are dead on at 100 yards, and also about dead on at 50, or sometimes slightly high or low. A sabotted muzzy round shoots pretty flat out to 100 yards or so - it is not like a shotgun slug in this regard. It is very possible that a 2" high setting at 50 yards can equal 4" high at 100. Sight your rifle in at 100 yards and then re-check it at 50....