This is a debate that could carry on adinfinitum.I would refer interested parties to the book," The Modern Shotgun", by Major Sir Gerald Burrard, Vol;2 "The Cartridge". The 306 pages of this book are largely dedicated to the analysis of,powder,pressure velocity and recoil[ie: not an easy read!]. Appendix 6,is relevant because it details; "The analysis of the internal ballistics of a 12 G shotgun."
I shall be interested to see the results of the tests planned for Gaugemates and to compare same with the various points of view expressed on this forum.

Roy Hebbes