help with vector3

I am trying to simulate bullet drop over time using vector3, I have already got bullet time but I get errors trying the bullet drop. what I am asking is can you or how do you make impactpos(Vector3) the hit point and times the Y axis by -bulletdrop?

 function fire () {
 //setting the var fwd2 to the foward position
 var fwd2 = transform.TransformDirection(Vector3.forward);
 //hit variable 
  var hit2 : RaycastHit;
  //ray variable 
  var ray2 = new Ray (transform.position, transform.forward);
  //detecting if there is a collition 
 if (Physics.Raycast (ray2, hit2, 100000)){
 //making smoke from the barrel
 Instantiate(smoke,transform.position,transform.rotation);
 //setting the bullet time to 0.003 * the distance 
 bullettime = hit2.distance * bulletinterval;
 //pointofhit = hit2.point; - trying other ways to get it to work 
 //get the bullet drop, drop * 0.003 or something as small 
 bulletdrop = hit2.distance * bulletdropamount;
 //the single line that does not work - just trying to set the variable 
 //impactpos to hit2.point with extended vector3 so i can subtract the bullet drop 
 impactpos = hit2.point(Vector3(hit2.point.x, hit2.point.y, hit2.point.z));
 // waiting for the time of the bullet to reach the target
 yield WaitForSeconds(bullettime);
 //creating the inpact for the explotion or other sparks 
 Instantiate(impact, impactpos, transform.rotation);
 
 } else { 
 // makeing smoke even though that there is no target in sight to simulate a miss
 Instantiate(smoke,transform.position,transform.rotation);
 }
 
 }

   

the error i am getting from unity is "It is not possible to invoke an expression of type 'unityEngine.Vector3'"