http://www.theboxotruth.com/docs/bot3.htm
Regarding bird shot, this is from the article:
When To Use Birdshot
A friend of AR15.com sends this:
"I saw a gunshot victim, about 5' 10" and 200 lbs, taken to the operating room with a shotgun wound to the chest. He was shot at a range of six feet at a distance of just over the pectoral is muscle. He was sitting on his front porch and walked to the ambulance. We explored the chest after x-rays were taken. The ER doc had said 'buckshot' wound, but this was obviously not accurate.
It was # 6 shot. There was a crater in the skin over an inch in diameter. When the shot hit the level of the ribs, it spread out about five inches. There was ONE pellet that had passed between the ribs and entered the pericardium, but not damaged the heart at all. As you say, 'use birdshot for little birds.'"