To get the aperture, centering effect, the hole has to be close to the eye. Mounted down on the barrel you have a hole, which is just an alternative to a notch. One may work better than the other for a given situation or shooter.
I was curious about this and got a fairly good discussion and pointers to literature when I asked about mounting a peep on a hand cannon pistol or long range single shot pistol. Bottom line, ZERO, benefit and nobody does it. I am sorry, I dont remember where I was. It is not a question of less benefit, there simple is none. None with regard to the aperture. Might be just the ticket for an individual for some other specific individual.
Wouldn't a peep on a handgun make it pretty much set for one yardage?
With a bladed rear sight there is a hard edge reference for positioning the front at varied elevations (some front sights have marks to help with that as well).
By holding the front high in the rear, you can shoot a longer distance and not cover up the target.
