cloned bullet will not destroy on collision

hey, so when i try and use the code below to destroy my cloned bullet it doesnt destroy, it doesnt even fire the onCollisionEnter event so i am very confused. the bullet has a collider and a rigidbody so i am very confused. any help is appreciated.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class shootScript : MonoBehaviour
 {
     public Rigidbody projectile;
     public Transform barrelEnd; 
 
 
     // shoot the gun *bang*
     void Update()
     {
         if (Input.GetMouseButtonDown(0)) {
             projectile = Instantiate(projectile, barrelEnd.position, barrelEnd.rotation);
             projectile.velocity = transform.TransformDirection(-30, 0, 0);
 
             Destroy(projectile.gameObject, 10);
 
         }
 
     
     }
 
     // destroy the bullet on enemy impact
     private void OnCollisionEnter(Collision collision)
     {
         Debug.Log("test");
 
         if (collision.gameObject.tag == "enemy") {
             Destroy(gameObject);
         }
     }
 }