I am replacing the coin adjustment knobs on a Lyman 57 apature sight with the finger type. The elevation knob was staightforward using a circlip to retain the screw, however the windage adjuster is a different story. I can't figure out how to release it....any tips?

Hutt,
Is there a tiny pin through the knob and the screw shaft? Have you got the new knob? Can you get any clues from it?

Cheers
Tony

afro408,
I have the new knob and it looks like it is retained with a tension plate between the sight itself and the adjusting knob. This tension plate appears to me to be staked or flush riveted together on either side of the knob. It is difficult to see what I am dealing with underneath the adjusting knob head.

Hutt,

I would call Lyman and ask them how to replace the knob.

The click spring plate has a hole in each end that sit over two pins that hold it in place under tension. It appears that if you were to lift both ends of the spring plate up and off the pins that the entire screw/knob assembly could pivot out of the slot. How you lift those up without damage I have no idea.

Is your new knob just a knob, or is it the entire screw?

It is an entire finger knob/screw unit.

quote:

Originally posted by Hutt:
It is an entire finger knob/screw unit.

I thought so...in that case see if you can lift the ends of the click spring tab off the pins and rotate/lift the whole unit out of the sight base. I believe that it is just the spring tension that is holding the knob/screw/aperature in there.

Before trying that though I would call Lyman about the proper procedure and what to use because you may end up bending the spring and needing to buy another one from them.