Some may say to not work the brass more than necessary. I try not to "bell" the neck, only enough to consistently seat a bullet with out damage or changing its size. 9mm is cheap and plentiful, not to worry about wearing out my supply.
My completed rounds often look slightly hourglass shaped. "Normal" Lee sizing die. This reduces bullet setback without over crimping. I never had any problems with used brass or discovered any particular reason to size smaller than what my dies already do. Again, 9mm is plentiful enough, either free or cheap enough to not hesitate to throw an undesirable headstamp or questionable case in the recycle bucket. I certainly would not spend time or money to "repair" a 9mm case.
