The Box O' Truth #44 - Shotgun Chokes and Buckshot
http://www.theboxotruth.com/docs/bot44.htm
The Box O' Truth #45 - Shotgun Chokes and Buckshot Part Two
http://www.theboxotruth.com/docs/bot45.htm
#91 - Let's Talk About Buckshot
http://www.theboxotruth.com/docs/edu91.htm
#46 - Shotgun Slugs, Sabots, and Smooth Bore Barrels
http://www.theboxotruth.com/docs/bot46.htm