It's kind of interesting. My dad has a Matthews z7 and the Ibo speed is with all of these specifications to the lightest stuff when it comes down to it its to light to shoot a deer with. My dad has a light set up and the Ibo is 320 or close to it shot it through a chronograph it was 280. Most bows will not Match the Ibo speed. I have a hoyt its Ibo is 300 it shot 260.
Very True. IBO Means two things:
First, The International Bowhunting Organization (IBO) uses a controlled testing system with draw weight of 70lbs, 350 gr test arrow, 30in draw length, and arrow speed measured at point blank. Any changes to this will affect the speed pretty significantly.
Chances are your arrows are much heavier, your string is heavier, probably laden with vibration-controlling devices, knocks, string loops, etc.. Short guys like me with 28" draw length.. all of these things 'significantly' slow down the actual real-world arrow speed.
Of course, the other meaning - I Blame Obama (IBO). Also a very reasonable explanation for your bow being slower than it should be