Hi,

I'd check to see if the scope mounts were tight first , (hey, it's cheap and easy to do). You don't say what brand of scope you're using, but you may have a problem with turrets not adjusting properly. They might allow some "slack" in the stadia during adjustment. You could possibly test this by making a downward adjustment and going at couple of clicks past what you want, then going back up to the adjustment you want.

Dale