Have a friend that will have to use a crossbow this year if he wants to continue bow hunting. He picked up a Horton Bone Collector, probably 3-4 years old. I have put 2 different scopes on it and cannot get it to come even close to hitting the mark at 20 yards. Scope is dialed up as far as it will go and still shoots about 5 inches low. Any ideas other than using it as a boat anchor?