There is more to the description of a ghost ring than to say it is simply a peep sight with a large aperture. Yes the aperture is larger than is common in a peep sight, up to a quarter inch, but where the peep sight has a wide rim (sometimes very wide) the ghost ring has a very thin rim. Thus simply drilling out the aperture of a peep sight does not necessarily a ghost ring make. The ghost ring's rim, "ghosts" out of focus, then out of your vision all together as you focus on the front sight. By contrast a target shooter's peep sight has a tiny aperture in a large disk that completely blocks the view except through the tiny aperture. While not very fast it is very precise. Where as the ghost ring is precise enough for practical marksmanship, it is also very fast to pickup.
That is why in my post I said to unscrew the disc and take it out, rather than just drill the hole larger. Here is a Williams Fool Proof with the disc removed, on a Marlin.
Note that the rim is very little thicker than is a Ghost Ring. A person used to peep sights leaves both eyes open and really couldn't tell you that a ring even exhists!


















































