The problem with Burrard and Thomas--both of whom had it right on the issue of long shells in short chambers--is that they can both be quoted out of context to make it seem as if they were wrong. One has to read all of Burrard's "Length of Cartridge" section, and all of Thomas' "Danger in Case-Length" chapter, to understand fully what they're saying.
It's also useful to remember that it was less common to find loads that met CIP pressure standards in 2 3/4" cases back when Burrard and Thomas were writing than it is now. There are all kinds of 67/67.5 MM cases out there now--some of which measure the same length as American 2 3/4" cases--loaded to standard CIP pressure. And it's even stated, right on the cartridge box, that such shells are appropriate in guns with 2 1/2" chambers.
