Twice in the last couple of weeks I have seen Super Blackhawk front sights on older revolvers for auction with an open notch that appears to be for a colored insert . One was a Liberty and the other an early 80's. Was this ever a factory maneuver or likely done by a gunsmith for someone ? I've been around them for about 40 years, owned several, ogled scads of them at shows and online auction sites and had never seen this before. Thanks.