I just set my Lyman Deerstalker up with peep sights. Here is what I did: The Thompson Center factory peep sight fits up EXACTLY with the existing tang holes, but I ordered the the extra TC mounting screws also...I think the Lyman tang srews worked okay though. The aperture of the TC sight wasn't vey user friendly...too small and didn't let in enough light. You can remove the entire TC aperture for a "ghost ring view, which some folks prefer anyway. For more precision, I also ordered an adjustable diameter aperture "Hunting Disk" #EB0804 from Dixie Gunworks...it is specifically threaded for the TC sight base. This is an awsome combination! Made a huge difference...shot two deer with it this season. I would prefer a smaller white bead on the factory Lyman front sight...it covers a 8"-10" diameter at 100 yards, but I think there is a smaller bead sold that I'll get installed before next deer season. Although it's subjective, I think the Lyman 57 peep isn't as "streamlined" looking as the TC peep and the TC sight was just as fully adjustable. Hope this helps...