Originally Posted by Jens Nordlunde
Imagine you had an arrow with a sliding weight on the haft. Before you took a shot, you pulled the weight back and when the arrow hit the target, the weight would make sure the impact was bigger than normal – would that work?
I don't think this would have any effect, but perhaps it might if the weight shifted from the fletch to the head at the time of impact. Because we are talking about a piercing shaft, all energy would be concentrated at the point of impact, and the mass of the arrow lines up directly behind that point -- so however mass is distributed behind the point of contact would be immaterial, unless possibly
if part of that mass is moving along the shaft at the moment of impact. Even then, I think the effect would be small and would need to be weighed against the effects of a rear-weighted arrow on its flight and accuracy. The small potential gain in penetrating power could well be offset by impaired accuracy.