I'm using Williams peep sights on several rifles with a Williams fiber optic front sight. To mount the peep sight on the rear of the barrel requires drilling and tapping the barrel, a gunsmith job.
I also have put the peep sight on the barrel in the same location as the original rear sight. I removed the peep insert, and have a mid-barrel "ghost ring". I use this with a fiber optic front sight. You'd be surprised how well this works.
Lock Haven, PA