This is my way of thinking. I practice long and hard with the best setup I can afford. I don't know how fast I'm shooting, all I know is that my arrow flies well. I am shooting a 406 grain arrow with a 100 grain tip. My thought is this, a heavier arrow will deliver a better punch on a larger animal if the shot is not perfect or if it is at a longer distance. For optimal penetration, I think weight is much more important than speed. For deer, I'm not too worried about either, but with elk, I want to be able to punch through as much of that animal as I can if I hit a rib or a shoulder or something like that. That is where I think weight comes into play. I personally don't think there is an exact number for any one setup. I think it matters how you and how your bow shoots your arrow. Shoot as heavy of an arrow as you wish, but make sure you are able to shoot your setup accurately. I think that is the bottom line. Everyone is more concerned about speed these days, which is always good, but you have to have weight behind it to help cut through everything. The way I think about it is this, if a pencil was traveling at a certain speed and a piece of metal the same size is going a little bit slower, which will penetrate further? The heavier slower one will. My 406 grain arrow is for deer and I will be bumping it up around 50 or so grains for elk if not more. I always like to say I'd rather hit something with a baseball bat than a rolled up newspaper. You can't swing as fast, but we all know which one will hurt more.
