Hmm... I'm new to this thread, so forgive me if this is a tangent.
Isn't the problem with running cast through the Glock 22 not a matter of leading/explosion from the rifling, but a matter of running "reloads" through the pistol and voiding the warrantee?
In my friends Gen-1, his spent factory rounds all have extensive bulging in the base of the case due to the rounds base not being completely shrounded in the chamber. It is not a headspace issue, nor anything anomalous as this is/was expected from this particular Glock. Note that the Lee and other "Bulge buster" dies that resize the spent cases all have disclaimers on them saying that they do not guarantee brass spent from .40 Glocks due to this issue.
Perhaps with new brass this would not present as much of a problem, and I know that many members here are much more knowledgeable on the Glock flavor than I. I hope that this stirs the nest a little, but doesn'tdetract from the subject.