FWIW, I turned up at the PJBRC with a set of clicks derived from Chairgun, and came second.
I'd zeroed at 25 yards, chronoed it, found the clicks for 55 yards from paper groups, then at home the night before the comp did all the others from CG. I found that CG was 2 clicks off real world at 55 yards but as it's a springer that's well within the error margin.
Wasn't really by choice. I took a day off work to get to the club a couple of days before the comp to set up properly like the other mortals. It was blowing half a gale, it was pointless.
I often use it to interpolate the intermediate ranges like 48 yards.