GunFollow.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GunFollow: MonoBehaviour {

	public GameObject objectToSpawn;
	public Transform gun;
	public Transform cam;

	// Update is called once per frame
	void Update () {
		Ray ray = new Ray(cam.position, cam.forward);
		RaycastHit hit;
		if( Physics.Raycast( ray, out hit, Mathf.Infinity )) {
			gun.LookAt (hit.point);
			if (Input.GetButton("Fire1")) {
				Instantiate( objectToSpawn, hit.point, Quaternion.LookRotation( hit.normal ) );	
			}
		}
	}


}