Problem when setting variable in an instantiated gameobject

The premise is this: I wanted to find a way to control the behavior of an instantiated bullet without having to make a different prefab every time,so I made a base Bullet class from which new classes can be created to override the Start() and Update() functions in the base class and then attach the new class to a GameObject. Here's the relevant code. Base bullet class:

 public class Bullet
 {
     public Weapon weapon;
     public Sprite bulletSprite;
     public Transform bulletBody;
     public float speed;
 
     public virtual void Start()
     {
         bulletBody.GetChild(0).GetComponent<SpriteRenderer>().sprite = bulletSprite;
     }
 
     public virtual void Update()
     { }
 }

The class I'm trying to get to work:

 public class NormalBullet : Bullet
 {
     public override void Start()
     {
         bulletSprite = Resources.Load<Sprite>("Bullets\bullet01");
         base.Start();
     }
 
     public override void Update()
     {
         bulletBody.Translate(bulletBody.forward * weapon.bulletSpeed);
     }
 }

The script on the actual bullet prefab

 public class BulletScript : MonoBehaviour {
 
     public Bullet bullet;     //This returns null after it is instantiated 
 
     void Start () 
     {
         bullet.Start();
     }
     
     void Update () 
     {
         bullet.Update();
     }
 }

and Finally were the bullet is instantiated (I pass a Bullet class previously created which is "bulletScript" to the prefab):

 public override void Fire()
     {
         GameObject firedBullet = GameObject.Instantiate(bulletPrefab,gunTransform.position,gunTransform.rotation) as GameObject;
         Bullet firedBscript = firedBullet.GetComponent<BulletScript>().bullet;
 
         firedBscript = bulletScript;
         firedBscript.bulletBody = firedBullet.transform;
         firedBscript.weapon = this;

         //If I check whether firedBullet has a "bullet" class set it says everything is as it should be
     }

When I try to fire the bullet it throws a nullReferenceException from the prefab I'm firing saying there's no Bullet class attached. I checked with Debug.Log and apparently the variable IS set the moment I instantiate the bullet but for some reason the Bullet variable on the bullet itself returns null. inb4 I'm actually blind and it was something really simple to fix.