I was wondering how people trim their 9mm Luger cases.
Thank you in advance.

They don't. Taper crip die no need to. I have loaded tens of thousands of 9mm never trimed a one or any other pistol case.

Don't need to. They don't really expand, and at $30 a thousand I woulod throw them away before trimming

Bob,
This is funny to ask but very real and a good question.
I trimmed the first batch of my (shot once) brass on my first time with 9mm reloading, and then figured it was unnecessary because of the limited stretch and a pain to do it because the cases are so small to work with. But to prolong the life and reuse - sometimes I will trim a tiny bit by hand without measure to keep the case mouth evenly flat (level) so it will chamber without problems or going past the chamber rim into the barrel. Of course I would only use loads from new fresh brass if I were to carry for protection.
Also considering how small the cases are to handle I ruled out ever owning a 380. “I don't like buying ammo”