I wanted a peep for the Triumph, and ran across this sight. I've never heard about it before, and never saw one mentioned on any forum. I don't know how long he's been making them, and it's the only sight he makes.
I got one, and i'm really impressed with it's quality. It's built to really take a beating, and I can't imagine it losing it's setting. It's dovetailed for elevation and windage with sturdy allen screws holding the adjustment. It's a longer, and uses the front and rear holes of the scope mounts holes instead of both rear holes like other peeps.
Have a look. Click on the pictures twice to get a blown up view.
http://www.sidelever.com/muzzleloader