Spreading bullet with rigidbody

hi, how can I spread my bullet. Here is my code

if (Time.time >= timestamp && Input.GetButton("Fire1"))
		{
			gunShot.Play();

			Rigidbody bullet;

			for (int i = 0; i < bulletCount; i++)
			{
				bullet = Instantiate(bulletPrefab, gunEnd.position, gunEnd.rotation) as Rigidbody;
				bullet.AddForce(transform.forward * 1500);
			}
			timestamp = Time.time + shotDelay;
		}

public GameObject spawnPoint;
public GameObject ExplosionPrefab;
public Rigidbody projectilePrefab;

    // Use this for initialization
    void Start () {
   
    }
   
    // Update is called once per frame
    void Update () {
       
        if(Input.GetButtonDown("Fire1"))
        {
            Rigidbody hitPlayer;
            hitPlayer = Instantiate(projectilePrefab, transform.position, transform.rotation) as Rigidbody;
            hitPlayer.velocity = transform.TransformDirection(Vector3.forward * 100);
//            Physics.IgnoreCollision ( projectilePrefab.collider, transform.root.collider );
 
   
         }
 
   
        for(var i =0; i < Input.touchCount; ++i)
        {
            if(Input.GetTouch(i).phase == TouchPhase.Began )
            {
            Rigidbody clone;
            clone = Instantiate(projectilePrefab, transform.position, transform.rotation) as Rigidbody;
            clone.velocity = transform.TransformDirection(Vector3.forward * 200);
//            Physics.IgnoreCollision ( projectilePrefab.collider, transform.root.collider );
       
       
            }
        }
       
       
       
    }
}