var bulletshell = Instantiate(bulletPrefab,shellSpawn.position, shellSpawn.rotation);
bulletshell.rigidbody.AddForce(transform.up + transform.right * 60);
bulletPrefab.transform.rotation * Quaternion.Euler(Random.Range(-10,10),0,0);
is where i instantiate it. i tryed Random.rotation but that is really ugly… But i can’t figure out how to add random rotation/force so when the bullet is instantiated it looks more realistic, Does someone know how to make this work 
Add a ConstantForce component to your bullet shell prefab, then add a script to that prefab. In that script, set the torque of the constant force to be random like so:
using UnityEngine;
using System.Collections;
public class Example : MonoBehaviour
{
Vector3 torque;
void Awake()
{
torque.x = Random.Range (-200, 200);
torque.y = Random.Range (-200, 200);
torque.z = Random.Range (-200, 200);
constantForce.torque = torque;
}
}
Have a look here for more info on constantForce.torque.
EDIT: If you want to do this in JS instead of C#
var torque : Vector3;
function Awake()
{
torque.x = Random.Range (-200, 200);
torque.y = Random.Range (-200, 200);
torque.z = Random.Range (-200, 200);
constantForce.torque = torque;
}