That is looking really good Gert and the warthog tusk should do the trick for finding the front sight in any ighting conditions. I expect you will shorten up the length of the bead itself when you get the size sorted. I have flat topped blades for all my aperture sighted rifles and have made the front sights .05 (1.3mm) but for a bead I would have thought about .08 (2mm) would be about right (you are not looking at a moon sight are you?).