The mater was actually settled in the late 1930's when the "Pie Crimp" shell was introduced to England. To put the standard load in a shell shortened by the fold/pie crimp which required more "Paper" to be turned down did not leave room for efficient wadding & also presented the danger of the shorter loaded length shells being mistaken for 2" shells. Experimentation was undertaken immediately of increasing the length of the "Empty" hull to the point that when given the fold crimp the "Loaded" shell length would be the same as the old roll crimped shell. Ballistics & pressures were found to be virtually identical. It is my understanding that virtually all British shells from that time forward, marked as suitable for a 2½ chambered gun are actually longer than the chamber they are intended to be fired in. While Bell's "Finding-out-for-Myself" project came to essientially the same conclusions his work in comparision with that done by the British gun & ammo makers just prior to & following WWII are about like a Kindergarten Science Project. They did however bring it to a lot of folks attention, so were good from that aspect. It had all been proven though, some 50-60 years before he undertook the project.
Statements at the time were twofold, the "Load" should be that for which the gun was intended "&" the "Loaded" shell should not enter the forcing cone. The fired shell opening into the cone seemed to present no detrimental effect, even with the thicker paper hulls & shorter cones (3/8"-7/16") then in use. Those findings are good enough for me. I also note the British have never had any qualms about proof testing a sound Damascus barrel for their loads which produce up to about 9,000 psi.
It is also noted that several US makers intentionally "Short-chambered" their guns intended for use with 2 3/4" shells by about 1/8".
Last edited by 2-piper; 04/04/08 09:37 PM.
