My buddy recently bought a chronograph and a grain scale, So we weighted our arrows and started playing around with the chrono. With my arrow weighing in at 460 grains, my bow maxed out (70-72) and at a 28.5 draw im shooting an arrow out of the bow at an average of 266 fps. Considering the ibo on the bow is 342 i thought that was a little slow , I know its a heavier arrow but wouldnt you think it would be shooting a little faster? I brought out an old parker phoenix 34 and it was shooting 245fps with the same arrow.Over all im happy with the kinetic energy numbers i got after using the calculator 73.08 lbs of kinetic energy just thought there would be more speed.
Your bow is on the slow side. I have a 60lb Monster 7. I shoot a 470gr arrow and I'm getting 265 with it. I'm guessing your bow could be out of tune or it could be time for a new string and cables. SCFox
IBO ratings for a bow are measured with a 30 inch draw, a 350 grain arrow, and a chrono that is set up at point blank range. I wouldn't worry about it
I'm not overly concerned but hearing the numbers of what other people are getting makes me think either some are stretching the numbers or I have a small problem. My bow shoots great I shoot out to 60 yards and do pretty well.