Aiming down a gun

Ive been working on an fps game in unity for a while now and are almost finished but im not sure how to create scopes and be able to look down them if anyone noes please can you help me

Okay, This is what I do:

static var ZoomOut = Vector3(0.265012, -0.1908424, -0.7531716); //Current Position of Gun

static var ZoomIn = Vector3(0.0135, -0.12, -0.8); //Position of Zoom (trial and error)

static var Zoom = false;

function Update () 
{
    if(Input.GetButtonDown ("Fire2"))
    {

            transform.localPosition = ZoomIn; 
            Crosshair.OriginalOn = false;
            Camera.main.fieldOfView = 40; //Turn off crosshair

    } 

        if(Input.GetButtonUp ("Fire2"))
        {

            transform.localPosition = ZoomOut;
            Camera.main.fieldOfView = 60; //default = 60
            Crosshair.OriginalOn = true;
            Zoom = false;
        }

}