Commenting out that line means you have to manually turn on the audio source which kind of defeats the point. It’ll play the audio right when the bullet shell is instantiated.
Note that you may have issues on the audio clip working dependent on the collider it’s hitting. Sometimes very small colliders, such as those on the bullet shell, seem to fall through thin colliders like that on a plane. Try using a box collider in the area where the shells would fall.
