SFP - If you demagnify, 1milrad could be half the fox. Fully magnify, 1milrad could be the foxes eye. Both magnification settings, including anything inbetween would give you different measurements. None of the scope magnification range can be right if its giving you entirely different readings. Only 1 setting, max magnification, is right.
If you take a shot and need to move say 1milrad, as soon as you adjust your magnification that measure is useless. Its like measuring the radius of the sun from earth with a ruler at arms length. Your ruler might say the suns radius is 4", its not an a