Years ago Bob Morrison did some experimenting with carbon arrows. He loaded up the point to get the weight up. Using the same shafting he added weight tubes to increase and achieve the same weight. Of the two types of arrows he found that the arrow with the weight foward rather than the one with the weight evenly distributed was significantly a better penetrator. I have found this to be true for myself. My assumption is that the weight distribution of the completed arrow has more to do with penetration, perhaps, than the diameter and maybe even shaft material. But even in that regard I have found that carbons out penetrate all other materials.