I've been using Williams peep sights on a variety of springers for the last two to three years. I find them more fun than scopes for target work up to 20m and more accurate than open iron sights.
Why more accurate? I think it has something to do with ones eyes and the need to focus on three items with iron sights whereas with peeps you concentrate on the front sight and target and ignore the rear aperture. It's similar to looking through a tiny hole in a sheet of paper or fence, you don't look at the paper or the fence, just the object beyond. The first cameras had pinholes and virtually everything viewed was in focus, it's similar with a peep sight and it seems to sharpen up my vision, and the same has been said by other forum contributors.
The model I bought is the Williams 5D-AG and that cost approx $45 from the States and about £30 off the Bay.
Which front sight element to use? That very much depends on a combination of target diameter and distance. Ideally when viewing say the black centre of a target the aperture you use should just give an image with a halo around the black. This aids the eye in resting the sights on the target and for some is easier to do than balancing a disc on top of a post type foresight as with iron sights. You can of course still use post sights if you prefer.
As mentioned not all HW rifles come with replaceable element type front sights, my HW99 is a good example. Heaven only knows why HW try to kid us it is replaceable by making the front sight look like the proper thing but with a fixed post only provided and no means of getting it out.
One complaint I have with the Williams is the size of screw used for the dovetail clamp. The heads are microscopically small and I immediately replaced mine with screws with a larger hex socket than the standard one fitted. The screws I bought only need a small torx socket to do them up and I only use finger pressure rather than use a handle and risk overtightening them.
hth
Jim
https://williamsgunsight.com/product/williams-5d-ag/
https://www.pyramydair.com/blog/2018...sights-part-2/ link to Part one shown in Part 2