Target Aperture Sight
Oh, I know the original poster was looking for a rugged field/ military type peep sight, but I just wanted to toss this out:
I got an Industry brand match-quality rear aperture sight. It's click-adjustable, has a .040 aperture, a soft rubber eye cup or shade, etc. It looks like a $200 unit, but it only costs $69 from Archer Airguns. It will mount to a tip-off scope base about .42-.44, such as the Weaver T-09 scope base ($8 available many places).
On a factory tapered 10/22 barrel, the only front sight that is tall enough to work is the Tech-Sight front sight unit, with the M16 type front post turned to a high setting-- about as high as the tops of the protective "ears" on either side of it. That will put it about 1.25 inches above the center of the bore, which will work well with the tall air rifle rear aperture sight.
On a Ruger 10/22 with a .920 bull or heavy barrel, it looks like the best thing to do is get a Tech-Sight dovetail adapter, and then order a Lyman globe-style front aperture sight with interchangeable inserts. The front sight needs to be about .87 tall, and Lyman makes one that's .85, which should work.
Here are pics of my 10/22 with an A.T. "fiberforce" Dragunov-style stock and the Industry brand rear sight from Archer Airguns and the Tech-sight front sight unit.