Help with my On_Bullet please

Questions & Answers
1 
var tempo : float;

var legno : PhysicMaterial;
var metallo : PhysicMaterial;
var pelle : PhysicMaterial;
var ghiaccio : PhysicMaterial;

var Hit_metal : Texture;
var Hit_wood : Texture;
var Hit_ice : Texture;
var Hit_skin : Texture;

var Hit_skin_part : GameObject;
var Hit_metal_part : GameObject;
var Hit_wood_part : GameObject;
var Hit_ice_part : GameObject;

function Update () {
         Destroy(gameObject,tempo);
}
function OnCollisionEnter(collision : Collision) {
 if (collision.collider.material == legno){
   Instantiate(Hit_wood_part, collision.contacts[0].point.zero,Quaternion.identity);//collision.contacts[0].point.rotation);
}

Destroy(gameObject);
}

But It don't Instantiate the Particle

2

Not really sure what you want this script to do, but it looks like your update function is always going to be destroying your gameObject everyframe.

Update your post with want your script is suppose to do, and what its doing now.