Problem with prefabs

I'm attempting to instantiate a weapon from a prefab to be use the game but for whatever reason every time I use the weapon the information in the prefab base keep changing inside of the copy? Is this some kind of bug or am I doing something wrong?

Here is the code that effect the prefab

 using UnityEngine;
 using System.Collections;
 
 public class ItemInfo : MonoBehaviour
 {
 
     #region properites
     #region type of item
     public bool Ammo;
     public bool Armor;
     public bool Conponents;
     public bool Flashlight;
     public bool Medical;
     public bool Misc;
     public bool RawMaterial;
     public bool IsEquipped;
     public bool Weapon;
     #endregion
     #region Weapon Type
     public bool Bow;
     public bool Pistol;
     public bool Rifle;
     public bool Shotgun;
     #endregion
 
     #region WeaponStats
     public int Shotfired;
     public float FireRate;
     public float timer;
     public float NextFire;
     public int Damage;
     public float force;
     public GameObject Projectile;
     public GameObject ProjectileSpawn;
     #endregion
 
     #region items base properties
     //doubles for ammo as well;
     public int HealthModifcation;
     public float NumOfUses;
     public float UseLimit;
     #endregion
     #endregion
 
     #region Functions
     // Use this for initialization
     void Start()
     {
 
     }
 
     // Update is called once per frame
     void Update()
     {
         timer = Time.time + FireRate;
     }
 
     void OnGUI()
     {
 
     }
 
     public void PrimaryFire()
     {
         if (Bow == true)
         {
 
         }
         if (Pistol == true)
         {
             if (timer > NextFire)
             {
                 GameObject projectile;
                 projectile = Instantiate(Projectile, ProjectileSpawn.transform.position, Quaternion.identity) as GameObject;
                 Bullet Bul = projectile.GetComponent("Bullet") as Bullet;
                 Bul.ShootForce = force;
                 Bul.Damage = Damage;
             }
         }
         if (Rifle == true)
         {
 
         }
         if (Shotgun == true)
         {
 
         }
 
         NumOfUses--;
         NextFire = timer + NextFire;
     }
 
     public void SeconaryFire()
     {
 
     }
 
     
     #endregion
 }