I can honestly say that of all the No5's I've ever seen, I've never seen that before and that is the sort of thing you'd definately notice. But never say never as they say. But that bring the next obvious question, How does the leaf sit down onto the bridge charger guide when what we call the 'landing platform' part of the sight (alongside the knob.....) has been machined away
In case anyone hasn't picked it out due to the dark pics, the rear of the leaf has been dovetailed.