How to change variables in another class?

Question

C++ / C#

I have a weapon script, there are variables there: Ammo, ExtraAmmo, ClipAmmo. They are responsible for the number of cartridges in the clip, additional cartridges and the maximum number of cartridges in the clip. There is a FireData method where it is checked if the cartridge in the clip is 0, then start reloading, but I can’t write how the weapon should be reloaded, because I don’t know what number in these three variables. I entered them as parameters, but how do I call this in Invoke? Is there a better way?

using UnityEngine;

public class Pistol : MonoBehaviour
{
    public int Ammo;
    public int ExtraAmmo;
    public int ClipAmmo;
    public float RateOfFire;
    public float ReloadTime;
    public float Damage;
    [Space]
    public bool CanFire;

    public void Update()
    {
        if(Input.GetButtonDown("Fire"))
        {
            Fire();
            FireData();
        }
    }
    public void Fire()
    {

    }
    public void FireData()
    {
        Ammo--;
        if(Ammo == 0 && ExtraAmmo != 0)
        {
            GunManager.StatsUI.text = "Reloading...";
            Invoke(GunManager.Reloading(ref Ammo,ref ExtraAmmo,ref ClipAmmo), ReloadTime); // Нужно string,а у меня void
        }
        else
        {
            GunManager.StatsUI.text = "You dont\nhave ammo.";
        }
    }
}

using UnityEngine;
using UnityEngine.UI;
public static class GunManager
{
    public static Text StatsUI;
    public static GameObject FirstGun;
    public static GameObject SecondGun;
    public static void Reloading(ref int Ammo, ref int ExtraAmmo, ref int ClipAmmo)
    {
        if(ClipAmmo <= ExtraAmmo)
        {
            ExtraAmmo -= ClipAmmo;
            Ammo = ClipAmmo;
        }else
        {
            Ammo = ExtraAmmo;
            ExtraAmmo = 0;
        }
    }
}

Answer 1

1. Not a variable, but a field.
2. To access them, you need to take an instance of this class.
It seems that the unit has some components that can be obtained via GetComponent

Answer 2

I would make variables that need to be changed from another class static (public static ammo;). And in another class I would do this

// Что-то до этого
Pistol.ammo = 7; // название скрипта, в котором находится переменная; точка; название СТАТИЧЕСКОЙ переменной; равно; нужное число;.
// Что-то после этого...

I don't really know if this works, but it's worth a try.