My 686-3 has an adjustible front sight, the blade of which is part number 324440. I would like to modify the blade such that it will accept fibre filiments. My thought is to remove the existing sight and silver solder or braze a sight base to the ramp that will receive fibre optic threads. What i can't tell, is if my existing sight is milled from solid metal, or if it is two piecesAnyone have thoughts or experience with such modification?

You could just make a new upper part that has a fiber optic sight in it and put that in place of the original. I'm assuming you are talking about the 4 position "Silhouette" sight.

Yes, 4 position silioette sight. But I don't have the milling capabilities that would require.

PM me and we'll see what we can work out.