I respectfully disagree with CJ.
The size of the aperture (within reason) has no affect on precision. The physical properties of a circle say that when light passes through a circle, the greatest consentation of light passing through the circle is at the center of the circle. The eye, when looking through a circle (aperture) automatically focuses on the point with the highest light consentration.
That is why an aperture is so fast. The proper technique for their use is thus: look through the aperture, pick up the front sight, put the front sight on the vital zone of the target, shift your focus back to the front sight for the shot. It is not necessary to align the front sight in the center of the aperture for the reason stated above. Just focus on the front sight and consentate on your trigger squeeze.
The tendency is to shift your focus to your target, as you want to see the impact of your bulllet strike. You need to overcome this and stay focused on the front sight until after the shot has been delivered.