Well Hotburn76 thanks for the info .....I'll check that pin / little bolt on his xbow next time we get together. I did check for any movement in the scope....front to back and side to side.....didn't see or feel any play.
It really seems that the POI is changing by heat and or humidity really.....had that bugger shooting right on for 5 final shots......put it carefully away.....next morning shot again, was off again , not even close to where it was the night before.
Don't get me wrong , he likes the bow , and I'm glad he does.....but I know he'll get frustrated soon and buy another scope for it, probably a cheap red dot type.
BOB in PA