I originally posted a similar question on the handgun forum but didn't get much response. Question: When installing new sights on a general purpose handgun is there a general rule of thumb as to what the relationship between the front blade width and the width of the rear notch should be? For example, assuming a 5 1/2" sight radius and a .130" wide front blade, what would be the ideal width for the rear notch on a semi-auto used primarily for short range defense?