I have seen more than a few contradicting articles regarding the need for crimping straight wall cased ammo. Specifically the 9MM. I currently do give mine a light crimp only because i don't feel comfortable NOT doing so. My Lee dies are new and they size the case wall to a smaller diameter than the inserted bullet. The finished rounds have a bell appearance and i am sure the bullet will be held in place sufficiently by this alone but i still give em a little crimp to ensure the flare on the case mouth is gone.What are your thoughts? Wanna kill these ads? We can help!