Find a video that shows how to build one from parts to be sure you have the basic setting correct. The knob turns to change the range setting when properly assembled, the screw locks the basic setting only. When you use the military sight in procedure with military ammunition your range setting should be pretty close to on target. Different ammo can require some shooting to see how close it matches your sight picture and may need some “ Kentucky adjustments” of your sight picture for best accuracy.

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