Penetration of Arrows
A hunting arrow with a properly sharpened tip or
head weighing in the neighborhood of
0.07 to 0.10lbs that has a kinetic energy of 50 to 60 ft lb, has
very little shocking power but amazing penetration.
Since for a given resisting force, depth of penetration varies
directly as the kinetic energy of the arrow it is better
to use a heavy rather than a lighter arrow.
http://archeryreport.com/2011/02/bow-efficiency-care/