frankthedm said:
An arrow with a head to cause equivalent blunt damage to a sling bullet would have laughable range since the arrowhead would drag the missile downward very fast.
Gah! No, no, nonono. You could attach a hippopotamus to the arrowhead and it would fall no faster. The trouble with a blunt arrowhead is that it is not sleek, and the trouble with a heavier-than-advisable arrowhead is that it takes too much force to accelerate. Your blunt head will slow your arrow down from air resistance, meaning that it will take just as much time to fall to the ground that a sleek arrow would have, but even if it left the bow at the same speed as the sleek arrow it will not cover as much distance in the time before impacting the ground.
Your heavy head will have any of a number of effects. If your bow is capable of applying enough force to the arrow quickly enough, the head's own inertia may snap the arrow's shaft like a toothpick between two fingers. If the bow is only strong enough to be optimal for regular, lighter arrows, it may not be able to apply enough force to get the heavy head up to the same speed, causing the same problem that the hippo-headed arrow would have.
This last scenario actually pretty well explains the behavior of the D&D blunt arrow: the range is reduced, because the heavy head only receives the same force from the bow, over the same bowstring draw distance, gaining the same amount of kinetic energy... and hence less speed for its increased mass. The arrow has the same kinetic energy, so it WOULD do the same damage to the target if it delivered the energy the same way, but it actually spreads the energy out over a MUCH larger surface area (compared to the pointy arrow, which has a surface area at its point of less than a square mm), thereby becoming much less lethal. It's still the same energy, though, so it's non-lethal damage instead of reduced damage.
D&D archery physics are crappy, but not so bad that they can't be justified to a reasonable level.