Marvin: If there's one thing I know, it's women and covert operations.
Frank: Marvin, that's two things.
Han Cho Bai: No, grasshopper. It is not.
When Han shoots at Bruce Willis and the others with the Gatling gun, we see cartridges on the ground. You can tell that they are all blanks. The tip is jagged and has been closed - live ammo just has an open hole where the bullet was.