I deliberately misspoke for simplicity sake, and yes; all you've said is correct.
Part of over gassing is the duration (Dwell Time) during which the overpressure is in effect. The extra 4" of barrel (24" bore) extends that time significantly. And yes, the loads were excessive, egged on by apparent lack of customary pressure signs on the fired brass; There were none except for sooting of the necks and shoulders, as well as a few partial case walls. Having never been presented with this sign, I incorrectly assumed that my pressure as good when it wasn't. I could not understand why the max loads showed no typical pressure signs on the cases, (I guess the 6.5G falls into its own category in that respect). When I reported this sign, the extractor was already broken (I believe), the advice here correctly diagnosed the cause (hot load combined with a longer dwell), and I proceeded to order the improved extractor, and break down all my remaining test loads. Clearly, by then I recognized that the aspects which killed the extractor were the extended dwell time (time the round takes to clear the bore beyond the gas port), and (I assume) reduction in extractor cross section as compared with the standard AR15 5.56 extractor. The enhanced replacement extractor showed considerably more beef in that area, which I took as assurance that my assumption was at least partly correct.
In any case, your statement about yanking the case out while pressure was still high is right on the mark, especially so since the dwell was extraordinarily longer than would have been customary. I used neither LeveRevolution nor CFE223 during load development, but W748 and TAC. Since the episode and repair, load testing was resumed using the same above propellants in more reasonable proportions (in agreement with published loads) with no additional incidents. I had learned some valuable lessons about developing loads for gas guns. As a further precaution, the 24" barrel has been reserved for varmint loads (90gr) only. FWIW I have an aversion to altering gas systems, and have yet to do any of that.
I will say simply that my load development experience with the 6.5G is atypical, and I have developed a skittish approach to it.
Serves me right for not taking my own advice about hotloading. Nice catch.
Greg