Colliders Not Doing Their Job

So I have a pretty annoying problem.

I've been using the FPS Constructor Weapons Package V 0.95 to throw some weapons together really quick, however, one weapon in particular, the rocket launcher, is not behaving like I would want it to.

Basically the rocket only hits the surface of my boxcollider-based floor about 80% of the time, and only hits my meshcollider-based surfaces about 10% of the time. Now I've heard about how mesh colliders can be worse for fast traveling rigidbodys etc. but I certainly am not going to manually put primitive colliders into my ENTIRE map.

I've heard of solutions to this "quantum tunneling" problem, that include raycasting and other techniques but I really have no idea where to start on this. Any input is welcome.

Here is the related script for the grenade/rocket function:

grenade.js

 var delay = 1.0;
 var timeOut = 1.0;
 var detachChildren = false;
 var explosion : Transform;
 var explodeAfterBounce : boolean = false;
 private var hasCollided : boolean = false;
 private var explodeTime : float;
 //private var hasExploded : boolean = false;
 
 function Start (){
 explodeTime = Time.time+timeOut;
 }
 
 function OnCollisionEnter (collision : Collision){
     if(hasCollided || !explodeAfterBounce)
         DestroyNow();
     yield new WaitForSeconds(delay);
     hasCollided = true;
 
 }
 function DestroyNow ()
 {
 //    if(hasCollided){
         if (detachChildren) {
             transform.DetachChildren ();
         }
         DestroyObject (gameObject);
         if (explosion)
             Instantiate (explosion, transform.position, transform.rotation);
 //    } else {
 //        return;
 //    }
 
 }
 function Update () {
    var direction = transform.TransformDirection(Vector3.forward);
    var hit : RaycastHit;
    if(Time.time > explodeTime){
        DestroyNow();
    }
 }

Thanks for all the help!

~TacoShank