Cross winds can play havoc with long distance. If there was a bad cross wind, you probably have your reason, or at second best, an excuse.

Unless you are a consistent long distance shooter, a distance like that can be intimidating to say the least. Many of use push enough bullets at 100 yards to feel very comfortable. I remember the first time I shot at 150 yards, I put them in a white paper plate, and was pleased with myself. I knew the rifle could do better so there was only one person to blame.

I found with additional range sessions at longer distances I became more used to the scope placement, and sight picture and the groups tightened up eventually. I am sure the same will happen to you. Your shooting a great bullet and an excellent powder charge. I'd guess it was a bad day on the range at long distance is all. Happens to me all the time.