Years ago, we had a member who was documenting Ithaca Flues failures due to cracked frames. As best I can recall, most of the failures were lightweight 20ga guns through which shooters often fired modern factory ammunition. Often the cheap stuff which was "light" only in terms of shot charge. Usually bought at local big box stores because of attractive prices. They had to produce enough punch to operate autoloaders which might have been cleaned last year or something like that.