"I zero'd in at 100 yards about week ago, and I didn't move the turrets because we ran out of daylight. Yesterday, I was getting ready to move my turrets up, when my friend told me I would need to move it DOWN. I was confused, but he went on to explain this is the phenomenon he's always experienced when he shoots on this part of the property (with all his guns). I bet him he was wrong."
So, you zero at 100, then your moving the elevation????? Then you wonder why your zero is off????? WTF???
Try this, zero at 100, dont touch the fucken scope AT ALL. Go to 300 shoot, get some data. Go to 200, shoot, get some data. Now, compare all your findings. And most of all, STOP LISTENING TO YOUR BUDDY! You never even established a baseline then started fucking with shit and wondered why shit was fucked up....