Originally Posted by 5teve L
Thanks for that Brian, intersting stuff, esp the 'crossover' theory.
If you draw it out on paper - you'll see that it can't be down to mounts. (not without being really really obvious just by looking at the mounts)
A bent barrel / wonky crowning, parallax error or something as simple as zeroing when there's more wind than you thought there was are about the only reasons for reported 'crossover' issues.
I've heard theories about scopes not being optically centred adding to 'crossover' problems, but I'm not sure there's any truth to the theories - I guess potentially there might be, but my money is barrel, parallax or wind.