Originally posted by 2-piper:
Note, that since the introduction of the fold crimp, nearly all British shells "Factory" loaded for the 2½" game gun have been put up in cases longer than 2½". Also note, as has been mentioned here on numerous occasions, several US makers intentionally chambered their guns about 1/8" shorter than the shells they were meant to fire for the purpose of "Improved Performance". In both cases the shells were longer than their chambers, & they were the shells the guns were "Meant To Fire". A thorough understanding of the reasons is far better than blanket statements, which is the purpose of this board.
Miller
That's a pretty darned good, concise summary. Fact is, the reason US manufacturers intentionally short-chambered their guns is precisely because those slightly short chambers and slightly longer shells DID improve performance--IF, by improving performance, you mean achieving denser patterns. If the old paper case mouths opened into the forcing cone, they provided some cushioning protection for the shot charge (no plastic wad, remember!) on its initial contact with the barrel. Hence, fewer deformed pellets; hence, denser patterns.
As for the misquoting between Bell, Thomas, and Burrard . . . I can't speak for Sherman Bell. However, it's pretty clear from Thomas' "Gun Book"--if one reads the ENTIRE chapter entitled "Danger in Case-Length" rather than quoting selectively--that Thomas did not misquote Burrard. In fact, the two reached essentially the same conclusion, in slightly different words.
Burrard: "It will be realised, therefore, that the increase in pressure is the result of the longer LOADED CARTRIDGE rather than that of of the longer UNLOADED CASE." (Emphasis Burrard's.) He then goes on to explain that it's the load rather than the case length that causes the danger: "Since 1946 I have tested many more lots and these results have proved quite definitely that for all practical purposes any increase in pressure due to the longer cartridge case really does not exist PROVIDED THE CORRECT POWDER AND SHOT CHARGES FOR A NOMINAL 2 1/2" CARTRIDGE ARE USED." (Emphasis mine.)
Thomas: "But in the particular case cited by Burrard, the main danger arises, not from the constriction when the cartridge is fired, but from the fact that the longer-cased cartridges he had in mind invariably carried heavier loads; and heavier loads in a given gun, USING A GIVEN POWDER, of necessity involve higher pressures." (Emphasis Thomas'.)
