What you are really saying is that this bow would shoot this 500 grain arrow at 233 FPS if it was set at 70 pounds.
That's not what he is saying at all. What he is saying, is that if the rep is correct in his findings, that this bow is very, very effecient at heavier poundages. BTW, if my calculations are correct, it would put a 500 grain arrow at 28.5" draw right at 280 fps, producing 87 ft. lbs of KE. There is no [X(] about that, just
and
.