I recently had a problem with a 9mm case (headstamp 9x19 C J 92) not sizing down enough to pass the "plunk" test. I loaded it, the loaded round failed the test, pulled the bullet, tried sizing it again and reloading it, and the loaded round failed again. At this point, I started to wonder if the case itself was out of spec, and lo and behold, after sizing it again, the case itself, with no bullet in it, failed the plunk test! (In each case, it appeared to drop into the chamber ok, but would not spin freely.) After this, I got out the calipers, and the mouth of the case seems to be in spec, but the base is a few thousandths too big. (Spec is .391" and this case measures .395") Is this case junk, or is it one of those times when something like an EGW "U" sizing die would be beneficial? I'm currently using an RCBS sizing die, which has been fine through several thousand rounds of loading.
Obviously I'm not going to buy a new sizing die in order to avoid scrapping one case, but I'm curious as to whether others have had similar experiences.