Lyman peep sight - what is the index on the side for?

[bison]

I just got an early Win M94 that has a Lyman peep sight mounted on the side of the receiver. In addition to the normal 1/4" moa per click screws to adjust elevation and windage you can move the entire sight vertically by pushing a little button and shifting it relative to the mount. There is an index that shows movement in this range that can be set to zero by loosening a screw that holds the sheet metal plate with the index marks and moving it up or down.

What is this for? I can't think of a reason you'd need to move the sight vertically once it's sighted in.

Thx

 

[Jim Watson]

You might want to set the scale so you could know the zero for different ranges. No counting clicks, just wind it up to the appropriate mark on the scale, or push the release button and slide it there.

 

[bison]

Makes sense. Thanks!

 

[35 Whelen]

Jim's right about the scale. The push button is so you can remove the entire slide in the event you don't want to use it, or it's interfering with something else. You have to be kind of careful because the little metal plate with the graduated marks also takes all the slop out of the slide when you tighten the screw that holds the plate in place.
35W