RE: carbons and recurves???
Hey Art--my fault that time. I didn't mean that you misunderstood, I was saying to Pete that I believe he misunderstood you. Dang computers.....
Nope, arrow weight isn't the only thing that affects penetration, but it is a big factor.
Ewolf, speed does play a part, but you don't want to give up momentum for speed. A 700 grain arrow travelling at 180 fps will out-penetrate one traveling at 150 fps, all else being equal. There is always that point of diminishing return too--you don't want to shoot an arrow that is so heavy that it drops to the ground at 10 feet (think that would be considered a spear anyway [8D]). I've never done any experimenting with that, but from what I've read it seems to be around 12-13 grains per lb of draw weight on average. That's when it gets to the point that the increased arrow weight will not make up for the speed lost.
It's the kind of stuff that makes my brain itch. I'm not going to get down to the bare minimum, so I'm not going to worry about doing the math just yet. My guess is I could kill a buffalo with a 70# bow, so I'm going with an 85# just in case.
Chad
(edited because I can't spell)