Simple question but I cannot get a consistent answer using different approaches. How to calculate the effect of velocity variability on target point of impact? a. With a 100yd zero, simply changing the velocity gives an answer which seems to be low. Since the velocity also affects the holdover required for the 100yd zero, and this is factored into the calculation, the downrange effect is minimized. b. So to reduce the 100yd effect, using a 1 or 25yd zero says the higher velocity hits LOWER downrange than the lower velocity. c. Using the same zero, and changing the ammo temperature sensitivity to alter the velocity, the calculated effect seems too large. Is there a ballistic program which allows a given velocity for zeroing, and a different velocity for shooting? Or is there a more "true" way to do this that I'm missing? Or should I just accept method "a" as being as close as I can get?