I've used the chart on Eder's and found it to be a little on the fast side, at least compared to a couple of chrono's. I tried it with two different bows and was shooting exceptional groups on the respective days--like less than 2 " at 40 yards. I only wish I was getting the speeds this chart says. My Freedom, according to the chart, was doing 294fps. The bow chrono'd at 264fps. I checked it wath my Martin SlayR recently and was clear off the chart at 330+ (my groups were just about 11" low). This bow actually chrono's at 293+.

Considering both tests, my results showed just about 30fps too fast using the chart, but consistently 30fps too fast. Maybe you could try it and just subtract that 30fps. Who knows? I do know for a fact that I can see a difference of 30fps and three different chrono's can't all be that wrong. Besides, I'm more inclined to believe I'm not getting 330fps with 55# and 27.5" draw, but 293fps is right in line with what most guys are getting with the SlayR.