Awhile back a No. 8 Ballard with a windage adjustable front sight followed me home.  It had a pinhead insert which I have trouble shooting.  I contacted Jim Kluskens of Distant Thunder as someone here on the list suggested.  I sent him my original insert for thickness, width, and height dimensions.  He made for me a few aperture inserts to my specified aperature and annulus dimensions.  I just received them today and they are first class.  If you need inserts lilke this, I would heartily recommend talking to Jim.
Phil

I believe the Ballard inserts are the same as Winchester. You can get insert cards from MVA, Buffalo Arms, and several other placesthat will fit those original sights..