Getting radius of a sphere

Hi, I have the following Problem. I have a predefined Zone, (sphere). Once the Players enters that Zone via OnTriggerEnter, he will start to Auto fire. At the same time this Zone will shrink by reducing the scale of the object.

This all works great, if the Player leaves the Zone he stops Shooting etc. However if the Player moves into the Zone and does not move he will shoot even after the Zone has shrunk to a Point where the Player no more is colliding with the Zone.

As far as I can tell the reason is that when shrinking an object, even though the collision box also shrinks it does not check if it is still colliding with other objects.

So as solution I was thinking of getting the radius of the sphere and check in an update function if the Players position is within the radius else stop Shooting. I don't really know how to Access the radius of one object and get ist current size.

Here are my two scripts ;

Player Attack

 var gun : Transform;
 var bullet1 : GameObject; //Blue
 var bullet2 : GameObject; //Yellow
 var bullet3 : GameObject; //Red
 var selectBullet : GameObject;
 var mayShoot : boolean = false;
 var fireRate : float;
 
 
 
 
 function OnTriggerEnter (col : Collider)
 {
     if(col.gameObject.tag.Contains ("Zone")) //Check for tag containing zone
     {
     mayShoot = true;
 
     InvokeRepeating ("Shoot", 0.0, 0.1 / fireRate);
     shooting = true;
     
     }
     if (col.gameObject.tag == "Blue Zone") //choose bullet1 when entering blue zone
         {
         selectBullet = bullet1;
         }
      if (col.gameObject.tag == "Yellow Zone") //choose bullet3 when entering yellow zone
         {
         selectBullet = bullet2;
         }
      if (col.gameObject.tag == "Red Zone") //choose bullet3 when entering red zone
         {
         selectBullet = bullet3;
         }
  
 }
 
 
 function OnTriggerExit (other : Collider)
 {
     if(other.gameObject.tag.Contains ("Zone"))
     {
         mayShoot = false;
     }
 }
 
 function Shoot()
 {
     if (mayShoot == true && CombatZones.mayshoot2 == true)
     {
     Instantiate(selectBullet,gun.position, gun.rotation);
     }
 }

And CombatZones

 var shrinkTimer : float;
 static var mayshoot2 : boolean;
 
 
 
 
 // check collision for player
 function OnTriggerStay(other : Collider)
 {
     if (other.gameObject.tag == "Player")
     {
         StartCoroutine(LerpScale(shrinkTimer));
         mayshoot2 = true;
     }
 }
 
 //start shrinking  
 function LerpScale(time : float)
 {
    var originalScale = transform.localScale;
    var finalX = transform.localScale.x;
    var finalY = transform.localScale.y;
    var targetScale = originalScale - Vector3(finalX, finalY, 0f);
    var originalTime = time;
  
    while (time > 0.0f)
    {
       time -= Time.deltaTime;
  
       transform.localScale = Vector3.Lerp(targetScale, originalScale, time / originalTime);
          
         yield;
             
    }
 }
 
 
 function OnTriggerExit (other : Collider)
 {
     if (other.gameObject.tag == "Player"){
     mayshoot2 = false;
     }
 
 }
 
 
 
 function Update()
 {
      
     //Destroy when reaching 0
    if (transform.localScale.x < 1)
    {
         mayshoot2 = false;
            Destroy (gameObject);
    }
 
 }