Originally Posted by long450
I bet your scope is not aligned with the bore. You can check by marking a 3 foot line on a target with a verticle level or plum bob. Start at the bottom and confirm zero then add ten minutes and shot 2 shots. Do it again atat ten more minutes. If the scope is aligned properly your impacts will be on or near the line, if not they will wander off to the right or left. Do this at 200 yards.
A slight cant in the rifle will do the same thing.
Need to both check the scope level relative to the rifle as well as checking to make sure the rifle is being held level.
As to the Op's question it could be the wind is changing on you between you and the target or it could be the above.
There is nothing harder to master than reading the wind. Pretty much every other variable can be accounted for with modern ballistic software and good marksmanship.