I want the heavier arrow for 3-D also. I am shooting 423 grains at 66# and traveling at 275 fps. Its no barn burner as 3-D goes at short ranges but there is more stored energy down range and will not give up the energy as fast as a lighter arrow. The 3-D game is won between the 25-35 yard range. I'm not willing to give away the gimme shots for an uncontrollable arrow. Too many people are giving into the speed game and really hurting themselves. I am able to outshoot the best in the valley on occasion without the light arrows. fancy magnified sights and stabizers that look like fishing poles. When it comes time to hunt I know my gear inside and out. No questions, just change the tip. Yardage judging is the single most overlooked part of practice. I spend more time on that then I do shooting. I could be the best shot in the world but if I don't know the yardage I will never hit my target. I would go with what shoots the best out of your bow and forget about chronograph numbers.ArthurP is correct. It is better to have a heavier arrow just in case. As for the mechanicals it is a known fact that they eat up alot of energy upon entry. Thats why I use a cut on impact two blade. This next comment will probably make ArthurP happy, I like to also use Zwickies with my compound. And no, I am not ready to give up my release quite yet!!!!!!!!!