Here's what Saxton T. Pope had to say about penetration in his classic and absolutely peerless book published way back in 1923:
"Hunting with the Bow and Arrow"
Shooting a blunt arrow from a seventy-five pound bow at a white pine board an inch thick,
the shaft will often go completely through it. A broad hunting head will penetrate two or
three inches, then bind. But the broad-head will go through animal tissue better, even cutting
bones in two; in fact, such an arrow will go completely through any animal but a
pachyderm.
To test a steel bodkin pointed arrow such as was used at the battle of Cressy, I borrowed a
shirt of chain armor from the Museum, a beautiful specimen made in Damascus in the 15th
Century. It weighed twenty-five pounds and was in perfect condition. One of the attendants
in the Museum offered to put it on and allow me to shoot at him.
Fortunately, I declined his proffered services and put it on a wooden box, padded with burlap to represent clothing.
Indoors at a distance of seven yards, I discharged an arrow at it with such force that sparks
flew from the links of steel as from a forge. The bodkin point and shaft went through the
thickest portion of the back, penetrated an inch of wood and bulged out the opposite side of
the armor shirt.
The attendant turned a pale green. An arrow of this type can be shot about
two hundred yards, and would be deadly up to the full limit of its flight.