I am no expert however, I think that once you get the gun zeroed the windage will not change at a further distance. I say this because your barrel and scope are out of align by a given moa value (in the given example it was a little under 6 moa at 100 yards). This misalignment is linear. If you are off 6 moa at 100 you will be off 6 moa at 1000 and therefore if no other external forces are acting on the bullet once you correct for the alignment problem it will be corrected at all distances. Again I am no expert but I have seen this in my own shooting. I have a rifle that has 15 moa left windage at it 100 yard zero. when I shoot it at 200 yards using my 100 yard zero the groups move down the target by 1.5 moa but are still in line with my point of aim. To fully prove this I should shoot at longer distances however, the further out you go the probability of an external force (extra wind) acting on the bullet increases.