ORIGINAL: spaniel
I center the front globe in the rear peep because my eye does that almost automatically. Then I know my bullet will impact right at the top of the front globe. By top of curature I mean the "north pole" of the globe, the very top top point on the circle you see as you look at it. The reason I like this as opposed to a blade is a blade gives you a WIDE horizontal line on the target, while the globe curves and gives you a nice precise point.