Something interesting I noticed after making this arrow and putting the measured FPS numbers into OT was that my bow speed increased. I adjust the IBO speed so that the calculated speed matches the measured speed and I had the IBO speed at 285 for a lighter (434gr) arrow. When I adjusted the IBO speed to get the calculated speed to match the 534gr arrow I had to increase it to 293. I am assuming that there was a more efficient energy transfer to the arrow with the heavier weight. I thought that was interesting.