Bob, maybe there is something to support your thinking in Shotguns & Cartridges (a book I don't have), but Garwood's essential conclusion in "danger in case-length" (pp. 260-262, Gough Thomas's Gun Book ) is that Burrard's thinking about long cases in short chambers is faulty in that long cases produce no large increase in pressure in the cones of short-chambered guns unless the long cases simply carry a much heavier charge of shot and powder than do the short; i.e., a charge which the barrels were not designed nor proofed for. Garwood specifically mentions crimped cases but does not mention nor distinguish paper or plastic. One might indeed think that the occlusion in the cones would be greater with relatively thick wall of paper cases and these must have been the ones predominantly or solely available during Burrard's life if not during Garwood's. Garwood is writing in 1964, certainly on the cusps of the adoption of plastic cases. I'd also like to hear more. I'm not familiar with the timeline for the changeover from roll to pie crimp shells altho I'm certainly old enuf to remember when over-the-counter shells were the former.
jack
