He may or may not have an optics issue, if worried about the heating, I"d just shoot 3 shots, let it cool some, shoot 3 more until I have 10 in the group.
That should answer if its barrel heating or not.
A good barrel, even a light one, should not walk like that.
OTOH it can also be a function of recoil, body position, NPA, and HOW you are looking through the scope, even though it shouldn't matter with optics, it can matter with optics.
IMHO without a correction on the knobs, I'm amazed that a scope would start to wonder some after a few rounds. That kind of shift with irons would be an NPA issue all day long.
But since I have never really shot optics other than on deer rifles a few shots here and there, you should know more than I for sure.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
