Simple Shooting Question

Hi guys, i was making a little shooting script to test some destructibility stuff and i'm having a little issue with the shooting.

For some reason the bullet won't go where i click on the left, it works fine when i click on the middle or the right but when i click on the left it just shoots towards the center.

Image for Clarification :

So could someone point out the issue thats causing it please.

I have a feeling its the normalise that is doing it but if i don't normalise the direction it messes up the shot completely.

Heres the if statement that handles firing the bullet.

         if (Input.GetButton ("Fire1") && canfire == true)
         {
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             RaycastHit hit;
             if (Physics.Raycast (ray,out hit, 300))
             {
             
                 Vector3 pos = hit.point;
                 GameObject go = Instantiate (bullet, transform.position, Quaternion.identity) as GameObject;
                 Debug.Log (pos);
                 Vector3 dir = pos - go.transform.position;
                 dir.Normalize ();
                 go.GetComponent<Rigidbody> ().AddForce (dir * force, ForceMode.Impulse);
                 timer = 2;
                 canfire = false;
             }
         }