Unless the heads are starting to separate, I doubt that the cases are weak. However, if the chamber they were fired in the first two times is sufficiently oversize compared to the new one, it is possible that when fired in the new chamber, they don't "shrink back" to the full-length sizing dimensions they were at when they were sized & then reloaded. This would indicate that the older cases lost some of the "springiness" the new ones have, so the old ones tend to remain a little larger after being fired. I believe this is due to work-hardening that resulted from firing and resizing them more times. But I do NOT believe the old cases are actually "weak" or dangerous to use. Just a PITA to extract! I would relegate the old ones to range use only!