I don't know from what you described if this is a possiblity but consider this. At longer ranges your arrow has a defined arc to it. Let's take 60 yards, when you are sighting your 60 yard pin, your arrow in flight, will cross your line of sight(from the pin, to your target) twice. On my bow, if I sight my 60 yard pin on a target at say 20 yards, i hit the target about 4 inches high because my arrow it still arcing towards it's peak elevation. Try this idea on your bow by literally, starting with that pin, set for twenty. shoot a target at 5 yards, then 10,15,20,25,30,35. Use a big enough target to prevent arrow loss, but sight that pin dead on a fixed spot on the target, for every shot. this will give you an idea of your trajectory and you will see if it is possible that your pin is giving you a "false" impact point on your trajectory arc