Answer by Kiyaku

Maybe try it like this:

Instantiate (bulletParticle, new Vector3(playerLocation.transform.position.x, playerLocation.transform.position.y,playerLocation.transform.position.z), Quaternion.Euler(playerLocation.transform.rotation.x, rotationParent.transform.rotation.y, playerLocation.transform.rotation.z));

• Add the "new Vector3" to your script (or just Vector3, i forgot about javascript)
• Add the "Quaternion.Euler" to your rotations so it gets delivered back as Quaternion

I don't know if there is a easier solution and if this really works 100% but at least i think it should work this way.

Hope this helps.