I have a book in my library titled "The Mysteries of Shotgun Patterns" by George G. Oberfell and Charles E. Thompson. 328 pages. Published by the Division of Engineering Research, Oklahoma State University Press, Stillwater, Oklahoma. Copyright 1960 by George G. Oberfell, P.O. Box 119, Bartlesville, Ok. Lots of good information including tables and figures,for example: