My former marine buddy says to use the very tip of the standard front sight to center on a target. Makes sense but I told him  fiber optic and tritanium sights have the dot a tad lower from  the tip of the front sight. That is what I just got on my Ar. So my quesion is: with a fiber optic front sight, do i place the actual dot on the target or on the tip of the front sight? The rear sight is standard except for the front with the red dot fiber optic. I'm new to this so forgive my simple question.