Well, a returning bear biologist has just sold me two boxes of Brenneke Black Magic Magnum slugs for a very nominal price. They are 5 round boxes that she's carried around the NWT for a couple of years and which, since her life indeed may depend on them, she now wishes to replace next year; she buys them personally and is vague about where and how but I don't need to know. The shells themselves look mint except that some of the black finish has been chipped off the tips of the slugs, I can live with that. I'll be looking for at least 10 more rounds of 'super slugs' and if nobody reports any further issues with the Challenger version, I may buy those.