Raycast shooting in the middle of the screen

I want my raycast shooting to be 100% accurate so it hits the middle of the map but I don't know how to do that. Here is my shooting script

 #pragma strict
 
 var damage:float = 38;
 var range = 100.0;
 var force = 10.0;
 var muzzleFlash : Renderer;
 var muzzleLight : Light;
 
 var UMPMenu: GUIStyle;
 var ReloadMenu: GUIStyle;
 
 var ReloadWarning = false;
 
 static var _UMPCanReload = false;
 
 var clipSize: int = 25;
 var bulletsInClip = 25;
 var bulletsLeft = 75;
 var allowfire : boolean = true;
 
 function Start (){
 muzzleFlash.enabled = false;
 muzzleLight.enabled = false;
 }
 
 function Update () {
 if(Input.GetMouseButton(0)){
 if(bulletsInClip >= 1){
 if(allowfire == true){
 fire();
 }
 }
 }
 if (Input.GetKeyDown (KeyCode.R)){
 if(bulletsInClip == 0){
 if(bulletsLeft >= 25){
 Reload();
 }
 }
 }
 if(bulletsInClip == 0){
 if(bulletsLeft >= 25){
 ReloadWarning = true;
 }
 } else {
 ReloadWarning = false;
 }
 if(bulletsInClip == 0){
 if(bulletsLeft >= 25){
 _UMPCanReload = true;
 }
 } else {
 _UMPCanReload = false;
 }
 }
 
 function OnGUI() {
 if(ReloadWarning == true){
 GUI.Label (Rect (Screen.width / 2.2, Screen.height / 2.5, 200, 200), "Press R to reload.", ReloadMenu);
 }
 GUI.Label (Rect (10, 650, 350, 350), "UMP .45", UMPMenu);
 GUI.Label (Rect (10, 700, 350, 350), bulletsInClip + " / " + bulletsLeft, UMPMenu);
 }
 
 function fire(){
 allowfire = false;
 audio.Play();
 bulletsInClip--;
         
 var direction = transform.TransformDirection(Vector3.forward);
 var hit : RaycastHit;
 
 // Did we hit anything?
 if (Physics.Raycast (transform.position, direction, hit, range)) {
 Debug.DrawRay(transform.position, direction * range);
 // Apply a force to the rigidbody we hit
 if (hit.rigidbody)
 hit.rigidbody.AddForceAtPosition(force * direction, hit.point);
 hit.collider.SendMessageUpwards("ApplyDamage", damage, SendMessageOptions.DontRequireReceiver);
 }
 
 muzzleFlash.renderer.enabled = true;
 muzzleLight.enabled = true;
 yield WaitForSeconds (0.04);
 muzzleFlash.renderer.enabled = false;
 muzzleLight.enabled = false;
 
 
 yield WaitForSeconds(0.2);
 allowfire = true;
 }
 
 function OnTriggerEnter(hit:Collider){
 if(hit.tag == "Enemy"){
 hit.transform.SendMessage("Damage",damage);
 }
 }
 
 function Reload(){
 allowfire = false;
 yield WaitForSeconds (1);
 bulletsInClip = clipSize;
 bulletsLeft = (bulletsLeft - clipSize);
 yield WaitForSeconds (0.3);
 allowfire = true;
 }