270 it may have something to do with the size of the objective and ring hight on your gun. The higher cross hairs are above the bore. This will I am assuming cause enough of a bore to scope angle change to have you zeroed again furthe down range. This meaning you will be high in between the 2 zeros. What I am trying to say is your pellet gun is sighted to cross line of sight at 20yds. In reality though the boer is pointed ever so slightly up that as pellet travels it is climbing. Gravity will over come the cliband pull pellet back across line of sight somewhere further down range. I hope this helps explain your dilema and I hope I am right.