Who knows what charge or what barrel these offending brass were fired from. I have three 9MM sizers, Redding, Lee, & RCBS, none of which will bring them all of them down below .392. The Lee has a tapered carbide insert, and does the best job of leaving no hump near the case head, while the Redding is the worst about leaving a big hump. The offending brass will not size down enough in any of them, no matter how tight I have the die against the shell plate.
I could send you some brass to try your sizer on. I have buckets of range brass. I can find some more over expanded cases right quick like. Might be those fellows shooting 9MM Major, which is why if my sizer won't bring it down to spec, I toss it. This same brass will feed, fire, and eject out of my other 9MM chambers, which are more generous.