,Why do I get the same value from object property?

,Hi everyone, I am stuck with a simple problem in my weapon script.

I have a non monobehaviour derived class where I set the [System.Serializable] attribute to make it appear in the inspector, but when I use this class in another and try to get my float value it always returns same value even though I change variable in inspector and the default values in the object itself.

Here Is the code :

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 [System.Serializable]
 public class BulletSpreading
 {
     public float minSpread = 0f;
     public float maxSpread = 0f;
 
     public float shootSpreadIncrease = 0f;
     public float spreadNormalizeTime = 0f;
 
     [HideInInspector]
     public float currentSpread = 0f;
 
     public BulletSpreading()
     {
         currentSpread = minSpread;
     }
 }
 
 [System.Serializable]
 public class ShootingData
 {
     public float fireRate = 0.1f;         
     public float reloadTime = 1.5f;  
 
     public int totalBullets = 50;    
     public int magazineCapacity = 5;    
     public int bulletsPerShoot = 1;
 
     //[HideInInspector] 
     public float fireTimer = 0f;
     //[HideInInspector] 
     public int currentBulletsCount = 0; 
 
     public bool IsMagazineEmpty { get { return currentBulletsCount == 0; } }
     public bool IsMagazineFull { get { return currentBulletsCount == magazineCapacity; } }
     public bool IsOutOfBullets { get { return totalBullets == 0; } }
 
     public ShootingData()
     {
         currentBulletsCount = magazineCapacity;
     }
 }
 
 public class GunBase : MonoBehaviour {
 
     // Point from where bullets and particle effects are instantiated
     public Transform shootPoint;         
 
     [Header("Main gun settings")]
     public ShootingData shootingData = new ShootingData();
     public BulletSpreading bulletSpreading = new BulletSpreading();
 
     [Header("VFX")]
     public ParticleSystem muzzleFlash;
     public GameObject shootParticlePrefab;
 
     bool IsReloading = false;
 
     public virtual bool Shoot()
     {
         if (Time.time < shootingData.fireTimer)
             return false;
 
         if (shootingData.IsMagazineEmpty)
             return false;
 
         // Get the next time for fire
         shootingData.fireTimer = Time.time + shootingData.fireRate;
 
         // Decrease bullet count by per shoot amount
         shootingData.currentBulletsCount -= shootingData.bulletsPerShoot;
     
         // Shooting effects
         ShootEffects ();
 
         return true;
     }
 
     public void Reload()
     {
         if (shootingData.IsOutOfBullets || shootingData.IsMagazineFull || IsReloading)
             return;
 
         StartCoroutine (ReloadCoroutine ());
     }
 
     public void ShootEffects()
     {
         if (muzzleFlash != null)
             muzzleFlash.Play (true);
 
         if (shootParticlePrefab != null) {
             GameObject shootParticleInstance = Instantiate(shootParticlePrefab, shootPoint.position, shootPoint.rotation);
         }
     }
         
     IEnumerator ReloadCoroutine()
     {
         // Set IsReloading var to true
         IsReloading = true;
 
         yield return new WaitForSeconds (shootingData.reloadTime);
 
         // How many bullets needed to fully fill magazine
         int amountNeeded = shootingData.magazineCapacity - shootingData.currentBulletsCount;
 
         // Check if we have needed amount of bullets 
         if (shootingData.totalBullets >= amountNeeded) 
         {
             // If so just decrease total bullets by that amount 
             // and give current count a fresh full magazine
             shootingData.totalBullets -= amountNeeded;
             shootingData.currentBulletsCount = shootingData.magazineCapacity;
         }
         else 
         {
             // If don't have needed amount than just grab the left outs and add to current
             shootingData.currentBulletsCount += shootingData.totalBullets;
             shootingData.totalBullets = 0;
         }
 
         // Set IsReloading false
         IsReloading = false;
     }
 }

When I try to get bulletSpreading.currentSpread it gives me 2f always instead of 0. If anyone knows what is the problem please help. Sorry for my English though.