I have thought a long time about the "short, fat" profile for rifle cartridges. Long before they became popular -- or even available -- it occurred to me that such a profile would burn powder more efficiently, and that we were too dependent on a very old cartridge design that probably has its roots in other considerations than best burning of the powder.
Some of the wording in the patent application just makes me raise my eyebrows, though. Does a fat cartridge really "place more of the propellent in proximity to the flame front of the primer? While it is true the flame front expands laterally (radially) at the same time it is progressing linearly toward the shoulder of the case, is it really closer (in proximity to the primer) than if it travels only linearly? I think that would have to be demonstrated empirically, and although I think it is probably so, I don't think we really know.
Another statement, though, really strikes me as questionable: "and reflecting more unburned granules rearwardly into the burning propellant where they are consumed." I suspect unburned granules are not reflected rearward in a cartridge case, especially as the flame is moving forward (and perhaps radially outward.) I would guess unburned granules remain in place while the flame front moves toward them.
All this is to question the wording of the patent application, not whether or not short, fat cases are the best. Looking at the historic development of bottle-necked cases from early examples like the .30 WCF and the early Mauser cases, I suspect their development was NOT optimized for burn pattern inside the case. I suspect, rather, that they were just a sort of progression from straight-walled black powder cases, into the smokeless powder realm, with the understanding that smokeless powder burns faster if it restricted -- unlike black powder, whose rate of burn is only dependent on granule size.
If we knew more about what happens inside a brass case we might discover that even shorter and fatter cases were better, or perhaps that the WSSM design is not optimally designed in terms of diameter/length and they are slightly too fat for their length. At the extreme, could the best design be a .30 caliber bullet with a case based on the .50 BMG and only 2.5" long? Conventional wisdom is that such a design would burn out throats too fast, but is that really the case?
Case length has probably been too much a function of the length of a rifle bolt, for example. Note that many early Mausers had 57 mm long cases, whether the bullet diameter was 7, 8, or 9 mm. That does not sound like optimization.
There is probably not much ROI in studying this further, but I for one would be interested in the results.
