Is it recomended or not to crimp a 9mm stock bullet?
A slight taper crimp is all you need - just enough to take the bell out of the case mouth and press the case against the side of the bullet. Since 9mm headspaces on the case mouth, you don't want to crimp enough to press the case into the side of the bullet, nor do you want a roll crimp (but then, I doubt any 9mm dies will put a roll crimp on the case anyway).
Just a Shooter