If your bullet impacts miss the vertical line it indicates the scope is not aligned to the bore. Fig. #2.
Simply mark a vertical line on your target using a level. Using your Scoplevel to verify
that your vertical crosshair is perfectly
plumb and using the bottom of the plumb line as an aiming point, shoot a group to verify zero. Elevate your scope's vertical adjustment
several minutes of angle between each shot until you reach maximum adjustment and shoot a group.
If your target looks like Fig #1. you are done. Your scope and bore are aligned and you
are ready for some serious long range shooting.
If your target looks like Fig. #2., let's fix it. Loosen the screws clamping your scope tube and slightly rotate your scope tube
in the direction of the group. (If the group is to the right, rotate the scope tube clockwise.) Re-tighten the screws and fire
another group. Repeat as necessary until your impacts look like Fig. #1. Then you will be ready for some serious long range shooting.