You have to sit and think about it. The sight is supposed to be straight up and down. It's leaning right. By adjusting to the left you're trying to pull the front sight to the left. If he goes out to 100 I think he'll find his error returns. Then he has to go further left. Return to 50 yds and you'll be shooting too far the other way. I've been through this a bunch of times already...that's why I have the tools to avoid this situation...now.