I am new to this forum but am looking for some help. I was sighting in my 300 wby mag after putting on an new scope ( Leupold VX3 6.5-20). I am shooting a load that has always shot well from this gun. I set it at 2 1/2" high at 100 yards (looking to be zeroed at 300). Gun grouped well - went out to 300 yards and held dead on and was hitting 5" high. Not sure what was happening - I dialed it back down and was dead on at 300 yards. Moved out to 450 and the gun was where it should be. Went back to 100 yards to see what was happening and was hitting 3" low. Someone please help explain this to me as to how this can be. Let me know what other info is needed. I appreciate any help. Thanks