Take a look at this photo. I shot these two arrows at 30 yards using a Bowtech Invasion CPX, the second-fastest bow in Bestul's recent test and the prize in our current scoring contest. The top arrow carries a 100-grain head, the bottom a 125. The point of impact is almost the same; so there's no reason not to use the heavier head, which as you can see above has a larger cutting diameter. (At 40 yards, by the way, the difference is only about 2 inches.) On a flubbed shot, which we all know is possible, the extra momentum and the bigger head could easily make the difference.