Peter most case failures do not result in injury to either shooter or gun. aside from bad nerves, of course!
this is a failure mode that gun designers have known about for roughly 100 years; plenty of time to work a "case failure" scenario into their destructive testing program.
the .45 crowd is very familiar with case failures in the 1911. again, a partially unsupported case, though 45 ACP is normally lower pressure than 40.
on re-reading Ankeny's post, I now realize that his "once-fired brass" has been once-fired by *him*, not purchased used. hope I didn't confuse anybody else.