Sharps 4590 is right on with that "ghost ring". Can't remember my Garand M-1 sight, but that was a big peep. Shot a collector's item (new) Winchester 94 .30-30 with an original tang peep sight, about 3/16 inch hole. From the bench, I shot 10 WWSX 150 gr Power points into 2.5" at 100 yards, 8 in 1.75". And I could see half the county through that sight! Darkhorse- the peep sight in the rear dovetail you refer to at Track must be the slide insert on page "Adjustable Rear Sights". Again, here you can use a big hole. Correctly, they are called "closed buckhorns". There is one on an original Hawken in the NPS musueum near the arch in St. Louis. Also an original rifle with a closed buckhorn in a museum in Des Moines. The idea is, take Track's Primitive Buckhorn sight #RS-A-59 and pinch the horns shut. I make my own. First fit an open rear sight to determine height of the center of that hole, then make the closed sight based on that center. Doc White shoots closed buckhorns. He says he usually places well in competitions he enters (or wins), and nobody has ever challenged that sight, calling it a "peep" sight. If they do, whip out your jeweler's saw and cut a tiny slot at the top. I like them, they are accurate and fast, and minimize eyesight problems. Horsedoctor- White's (Shooting System?) (inline) catalog I can't find at the moment shows their sight, seems to have about a 1/4" hole in that tang peep. They work great for low light or fast snap shots.