Seeking Lyman 21 elevation stop screw | Winchester Swap Meet | Forum

I am searching for a longer elevation stop screw for a Lyman 21 rear sight. I need one about 0.375" in length. It’s the small screw positioned left of the aperture that limits the amount that the sight can be lowered by contacting the top of the receiver. A reproduction screw would suffice. Does anyone know the size and thread pitch of the screw? I suppose a machinist could make one too.

I appreciate all leads. Thanks.