Peep sights on rifles, with a large aperture, are very fast and reasonably accurate. Rifle peeps with a small aperture can be the most accurate of all iron sights. Just looking through an aperture sharpens the image of both front sight and target. But to secure that advantage the peep must be close to the eye. Peeps mounted on handguns or out on the barrel of a rifle are too far from the eye so that you are looking AT the peep rather than through it and it then becomes just an obstruction of the view, not a good thing at all. Plain open sights combined with a stick-on aperture on the shooting glasses work very well because again the aperture is close to the eye.