1H21-22 is Marina's testimony. Nothing about dry-firing.
McMillan's claim is unsourced.
I can't find anything in CE 1154 having to do with a rifle at all.
Yeah but, as I understand it, most of the McMillan book is from interviews between herself and Marina. In which case
Marina would be McMillan's source. That's what I meant when I said it's going to be hard to prove, only Marina can confirm or deny this and she's not exactly responsive to answering questions these days. Also, of course, Marina's 'word' is worth zilch to many, if not all CT's!