Shooting and Flash

I have a shooting script where you press to shoot and then it calls a function. Then it should instantiate a flash object, and disappear after 0.2 seconds. The problem is the shoot function stops calling immediately after its called, making it not possible to destroy.

using UnityEngine;

using System.Collections;

public class Shooting : MonoBehaviour

{

public float fireRate = 0.25f; private float nextFire; public GameObject spark; public GameObject flash; public Transform gunTip; public LayerMask layer; public float range = 10f; public float flashYield = 0.2f; private float nextFlash;

 void Start () 
 {
     nextFire = fireRate;
     nextFlash = flashYield;
 }

 void Update () 
 {
     if(fireRate < nextFire)
     {
         fireRate += Time.deltaTime;
     }

     if(Input.GetButton("Fire1") && fireRate >= nextFire)
     {
         Shoot();
         fireRate = 0f;
     }
 }

 void Shoot()
 {
     Vector2 mousePos = new Vector2(Camera.main.ScreenToWorldPoint(Input.mousePosition).x, Camera.main.ScreenToWorldPoint(Input.mousePosition).y);
     Vector2 firePoint = new Vector2(gunTip.position.x, gunTip.position.y);

     RaycastHit2D hit = Physics2D.Raycast(firePoint, mousePos - firePoint, range, layer);

     FlashF();
     SparkF();
 }

 void FlashF()
 {
     GameObject flashClone = Instantiate(flash, gunTip.position, gunTip.rotation) as GameObject;
     if(flashYield >= 0)
     {
         flashYield -= Time.deltaTime;
     }
     else
     {
         flashYield = nextFlash;
         Destroy(flashClone);
     }
 }

 void SparkF()
 {

 }