http://www.freerepublic.com/focus/f-news/2897417/posts#16
Shotgun penetration in the gelatin block shots are very graphic and easy to understand.
http://www.thetruthaboutguns.com/2010/02/robert-farago/shotgun-penetration-with-various-rounds/
But I believe from experience the following negates the results of this test.
All of these shots were taken from a known distance and angle into bare Ordinance Gelatin in a controlled environment. This does not take into consideration the effects clothing, weather, range, temperature, cover, or body structure.
I watched a friend get shot in the butt while wearing heavy insulated coveralls, like Carhartt, tough outer material.
The bird shot that was being used tore up the outer fabric layer but not a single pellet broke the skin.
After the shootee got off the ground (he was leaning over to tie a bootlace) he beat the crap out of the novice kid walking with his finger on the trigger.
In light birdshot, clothing makes a big difference. The Box O’ Truth Web site uses denim cloth in their penetration test.