Raycast to crosshair. Script change.

So I made a gun shooting script that uses raycast, but I want to make it where the gun shoots at the crosshair at the middle of the screen no matter where the gun is positioned. I have a gun script made already I just need it modified to shoot like I want it to.

 #pragma strict
 
 
     var spawnPoint : Transform ;
     var speed : int;
     var nextFire = 0.0f;
     var fireRate = 0.1f;
     var ammo = 150;
     var ammoText : GUIText;
     var shotSound : AudioSource;
     var wood : Transform;
     var sand : Transform;
     var dirt : Transform;
     var water : Transform;
     var enemy : Transform;
     var range = 100;
 
     
     // Update is called once per frame
     function Update () {
         
         if(Input.GetKey(KeyCode.Mouse0) && Time.time > nextFire)
         {
             if(ammo > 0)
             {
                 Shot();
                 audio.Play();
                 ammo --;
             }
         }
 
 
     
     }
 
     function Shot()
     {
         nextFire = Time.time + fireRate;
 
         var hit :  RaycastHit; 
         var fwd = spawnPoint.TransformDirection(Vector3.forward);
 
         Debug.DrawRay(spawnPoint.position, hit.point);
 
         if(Physics.Raycast(spawnPoint.position, fwd, hit, range))
         {
            
            if(hit.collider.tag == "Dirt")
            {
                Instantiate(dirt, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
            }
             if(hit.collider.tag == "Sand")
            {
                Instantiate(sand, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
            }
             if(hit.collider.tag == "Wood")
            {
                Instantiate(wood, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
            }
              if(hit.collider.tag == "Water")
            {
                Instantiate(water, hit.point, Quaternion.identity);
            }
                if(hit.collider.tag == "Enemy")
            {
                Instantiate(enemy, hit.point, Quaternion.FromToRotation(Vector3.forward, hit.normal));
            }
         }
 
     }
 
     function OnGUI()
     {
         ammoText.text = "Ammo: " + ammo.ToString();
     }