bigbulls

Because the heavier arrow retains a higher percentage of its available KE and momentum over greater distances. In other, words the lighter weight arrow bleeds off velocity at a much faster rate than the heavier arrow so the farther you are from the target the less penetration you will have in comparison to the heavier arrow.

Should you not make a perfect broadside shot through the ribs the heavier arrow will have a much better chance of getting deep into the vitals through heavy bonethan the lighter weight arrow will.

The bow is much much quieter with a heavier arrow.

There is much much less stress on the bow (limbs splintering) when shooting heavier arrrows.

There is much less hand shock and vibration with a heavier arrow.