That doesn't work that way with my bow at all. If I shoot a 314 grn arrow at my target from 40 yards and hit the center, then shoot a 416 grn arrow and aim at the same spot it will not even hit the target. It drops more than a foot compared the lighter arrow. Small weight changes my react differently, like 25 grns or so, but when the difference is considerable heavier arrows drop more, period.

Another thing we are not taking into consideration, but Aurthur aluded to is sight paralex (sp?).
The distance your sight is above your arrow will give you the perception that your bow shoots flatter. Works the same with rifle, the higher your scope mount is it will make your rifle seem to shoot flatter out to a certian yardarge.

Use the ballistic calculator at Jacksons site to check the drop of an arrow, it does not compensate for sight height. Then try one that does, like middletons, although his tables don't work on my computer any more. I don't know if it's his site, or the Java on my computer doesn't work right. You could use a ballistics calculator for firearms if you knew the ballistic coeficient for your arrow though. At any rate I am pretty sure the one that compensates for sight height will show a flatter trajectory. I could be wrong however, it's happened at least twice before that I'm aware of.

And like everyone is saying, the key is if they travel at the same speed, which isn't going to happen out of a bow.

Paul