(a) It is a good idea to mark the sight adjustment screw with a small drop of nailpolish or airplane dope to indicate the position of the 25 yard and 50 yard zero.(b) You may also set the elevation screw down to its lowest point, counting the clicksas you do and record the number of clicks up from the bottom for both settings,This way you record the number of clicks from the base of the sight up to your 25yard and 50 yard zero. (This method is used only for elevation. )(c) You may also make a sight adjustment card on which you can record the zeroposition of the windage and elevation screw for all weapons. At certain times ondifferent ranges, and under various weather and light conditions, you may findyour zero changes slightly. (Figure 4-2).