TW;
I also recall reading a statement by a balistition but likewise cannot remember who nor where. I seem to recall though it was in some old loading manual I had. Anyway he stated he could load a shell to about any pressure level you wanted just by varying the crimp.
Keep in mind that smokeless & black are totally different in their behavior. Black ignites easier & then burns at essentially the same rate regardless of conditions.
Smokeless on the other hand is harder to ignite & normally requires some resistance to build pressure. Once it starts to burn though the more pressure it builds the faster it burns & thus the more pressure is built. Retard it just a bit too much & it can become dangerously high, even with the crimp opening normally. If the crimp holds long ough to break an otherwise good condition case I would have Absolutly No Doubt that chamber pressure would be excessive, irregardless of the actual breaking strength of the case.
I recall an article by Don Zutz once where he had tested some shotshells using plain white flour as a buffer. As long as they were fired fresh pressures were normal. After sitting for a while though the flour attracted moisture & caked & clung to the walls of the roughened walls of the previously fired hulls. Pressures went dangerously high. I highly suspect if you had of had some of those loads with the Mono Wads which stretched the cases pressure tested you would have found them excessive as well.
