gun problems

There are couple of ways to approach this. If you simply want to fire a bullet then the easiest would be to do the following.

 void Update()
 {
     Vector3 directionOfFire = Vector3.forward;
     float bulletSpeed = 10f;
     gameObject.transform.Translate(directionOfFire * Time.deltaTime * bulletSpeed);
 }

But if you want to move a bullet from one fixed point to another (which is not how it normally happens, but still might be a requirement in your game) the following might help you.

  private float m_DeltaTime = 0f;
  private Vector3   m_StartPos;
  private Vector3   m_EndPos;
  
  void Start()
  {
     m_StartPos = Vector3.zero;
     m_EndPos = Vector3.left * 100f;
  }
  
  void Update()
  {
     if(m_DeltaTime < 1f)
     {
        m_DeltaTime += Time.deltaTime;
        gameObject.transform.position = Vector3.Lerp(m_StartPos, m_EndPos, m_DeltaTime);
     }
  }