Thompson/ Center Hawken peepsight
I have a 54cal Renegade with a 30" round ball barrel. This spring I had the TC tang mounted aperture sight installed by a local gunsmith. I used the back screw and had the smith drill and tap a hole for the front. In addititon I put a Lyman A-17 front sight on too. The A-17 has 6 interchangeable front sights as well. I find my groups are much tighter now and it is easier to aquire my target. My eyes aren't what they used to be and I find an aperture sight to be just the ticket for these tired eyes.
Also, I find the comb on my Renegade to be a bit high and with the tang sight and A-17 I get a good comfortable fit now.
Good luck, Jim