Thanks for sharing this with us, Lynn. I'll go on record that I believe the sight to be a highly modified Lyman #29, originally intended for a Savage 1899/99. Whoever modified it did a swell job of removing the forward part of the base that conforms to the 99 top tang, installed knurled opposing windage adjusting screws to replace the inconvenient original slotted head ones, and as you pointed out, the stop pin (which eliminates one of my pet peeves about the sight in that precise vertical "stabilization" is nebulous at best). Attaching it with hidden screws from underneath is obviously necessary, but a neat application nonetheless.
