I always enjoy reading your posts, Kraig. Very informative and insightful.
As for the OP's post, the most common error I see with pronghorn hunters, especially myself, is obtaining correct range to the distance of the antelope. I'm a recent convert to pronghorn hunting and the first few seasons, my missed shots were due to inaccurate range estimation. Or as Kraig said:
I've seen many times people estimating the range to the critters and finding out they are sometimes up to 200 yards off.
I stopped by a group of out of state hunters glassing a mid size buck. They were guessing anywhere from 300 to 480 yards.
I used a range finder and showed them it was 228. I then used a map and protractor which confirmed about 225.
...sad thing is that I WAS using a rangefinder.