My bullets just fall to the ground

I am trying to fire a bullet forward from a transform called BarrelEnd, but my bullets just spawn at BarrelEnd and they fall to the ground, how do I fix this?

Here’s my script:

var AmmoInPocket = 240;

var AmmoInCurrentMag = 30;

var MuzzleFlash : GameObject;

var MuzzleLight : Light;

var RoundBursting = false;

var ReloadAudio : GameObject;

var Cam : Camera;


var BarrelEnd : Transform;


var Bullet : Rigidbody;


var HipPose : Vector3;

var AimPose : Vector3;

function Start () {

  transform.localPosition = HipPose;

}

function Update () {


  if(AmmoInPocket < 0 ){
  
  
  
  AmmoInPocket = 0;
  Debug.Log("Player has no more ammo for ACW-R");
  
  
  }
  



//while(RoundBursting){

//MuzzleFlashFunc();
//MuzzleLightFunc();

//}

  if(Input.GetKeyDown(KeyCode.R)){
  
  if(AmmoInCurrentMag < 30 && AmmoInCurrentMag > -1 && AmmoInPocket > 0){
  animation.Play("ReloadACW-R");
  AmmoInCurrentMag = 30;
  AmmoInPocket -= 30;
  ReloadAudio.audio.Play();
  }
  

  
  }


  if(Input.GetButton("Fire2")){
  
     transform.localPosition = AimPose;
     Cam.fieldOfView = 40;
  
  
  }


 if(!Input.GetButton("Fire2")){
  
     transform.localPosition = HipPose;
     Cam.fieldOfView = 60;
  
  
  }



  if(Input.GetButtonDown("Fire1")){
  
  var BulletPrefab : Rigidbody;
			BulletPrefab = Instantiate(Bullet, BarrelEnd.position, BarrelEnd.rotation) as Rigidbody;
   BulletPrefab.AddForce(BarrelEnd.forward * 40);
   
  
  if(AmmoInCurrentMag > 0){
  AmmoInCurrentMag -= 1;
  AmmoInPocket -= 1;
  
  audio.Play();
  
  MuzzleFlashFunc();
  MuzzleLightFunc();
  
     }
  
  }
  
 

}

function MuzzleLightFunc () {

   MuzzleLight.enabled = true;
   yield WaitForSeconds(0.04);
   MuzzleLight.enabled = false;


}


function MuzzleFlashFunc () { 


MuzzleFlash.renderer.enabled = true;
yield WaitForSeconds(0.04);
MuzzleFlash.renderer.enabled = false;



}
,

Add more force, like 4000. If its falling through ground something is wrong with the colliders. If the ground has mesh collider attached, tick convex for bullet.