cave62, it may just be a combo of things. You have a little extra weight on the string as opposed to those that only have a peep and loop on their string, you have a 29" DL so will lose about 10fps right there from IBO, your losing some more with the extra 40grns in weight on arrow, your bow may be somewhat out of spec/tune, and IBO's for most bows in most cases are stated as higher than they actually are.