Why are my Mult-A-Range scope crosshairs unevenly

The Mult-A-Range scope reticles are spaced according to the average trajectory of a 175-pound crossbow. Due to the changing trajectory, the space between 20 and 30 will not be the same as the space between 30 and 40 and so on. The added affect of the 4-power magnification further distorts the spacing to the eye.