I'm about to start reloading for .40. When I was shopping for dies, I saw some criticism of Redding .40 carbide sizing dies marking the webbing section above the extractor groove. I did some further research, and it seems that Redding recommends that for .40/10mm, they recommend not adjusting the sizing die to touch the shell plate with their normal sizing dies, carbide or not. Their explanation is that with .40S&W, if the carbide ring is set up to size the base/head/web to the right size, it leaves the mouth too large for optimum bullet tension and increases the chances of bullet setback. They say that has been a running problem with .40 from all manufacturers, and that their (Redding's) solution was to re-spec the carbide ring to size for proper bullet tension on the upper half of the case and advise not to do full case re-sizing. If you do full-case re-sizing with these dies, it will overwork the lower webbing area of the case. Redding has since released a "dual carbide ring" sizing die for .40 (and a few other straight-walled cases) that sizes the mouth and base with different rings, each to the proper size. These seem to be out of stock everywhere I looked.
So here are my questions:
Is anyone familiar with this issue?
If this is true, might the under-tensioned, setback prone .40 sizing dies out there be responsible for the disproportionate frequency with which .40 suffer KB's?
Might using Redding's normal die and full-length resizing, over-working the webbing, result in weak webbing and KB's?
Might using Redding's normal die and not full-length resizing leave cases out-of-spec at the base and result in out-of-battery KB's?
If I could have found one of Redding's dual-ring sizing dies for sale, I probably would have bought it, even at the $90 price tag for the one die, and never asked. But that doesn't seem to be an option.
Any thoughts appreciated.