I like to shoot old revolvers but the sights make good shooting difficult, especially for old eyes like mine. Basically the notches are too small or the wrong shape. In the few cases in which I have done a little modification I have found that making the rear notch a bit wider and deeper really helps. I do better if I can float the front blade or bead in the rear notch with a little space around it. My question is, what is the best way to increase the rear notch size on an old solid frame revolver, say, an H&R 922. I suppose it is a matter of filing for an amateur, but what kind of file and what technique? Any tips on such a process would be appreciated.