They were made for the now almost dormant sport of metallic silhouette shooting where steel targets having the profile of different game animals were shot at from four different yardages, with the targets becoming larger and heavier as the yardage increased. The idea was that by simply moving the front sight, a shooter could have the same sight picture for all four targets.

Setting it is easily done but I forget if you go from short yardage to long or vice-versa. You could zero the gun at 25 yards with the front sight all the way up and then repeat the process at 50, 75 and 100 yards, each time moving the front sight down one notch and adjusting it to a perfect zero. Or it might have been start at 100 and move it up each time.

In a perfect world, once zero was found for one yardage, the rear sight did not have to be adjusted.

Ed

I just read frog's post and have to disagree. I shot PPC many years ago and the yardage variation was so small - 7 to 25 yards - that sight adjustments not only were not needed, we never had time to play around with sights between relays. You sighted your gun in at 25 yards and "pointed" the closer targets, which were life-size human silhouettes.