Those are just my own personal minimums. I'm not saying you can't kill an elk with a lighter arrow; lots of people do. But I think penetration is much more important than speed on big animals like elk and I don't want to sacrifice it to a longer shooting range. I haven't shot many elk, but I've never had an arrow go completely through. I shoot 425 grain arrows at around 265 fps. I don't believe KEtells the true story of penetration.