Took my Buck Mark to the range and shot 400 rounds, I am new to this sport and hit the target most of the time but I really don't know how to use the sights. The rear sight is a rectangle open at the top and the front sight is flat on top and straight on the sides. The Question is do I align the top of the front sight to the top of the rear sight and in the middle or the top of the front sight to the bottom of the rear sight in the middle????