The longer, full fix with working extended magazines and attachments:

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in private void Start()
change
UpdateSpriteforLoaded("standard");
to
UpdateSpriteforLoaded(gameObject.GetComponent<AmmoUsageBehaviour>().ammoLoaded);

---

You have to add this fix to every AfterSpawn in weapon (this example is for AK47):

---

ModAPI.KeepExtraObjects();

Instance.GetComponent<SpriteRenderer>().sprite = ModAPI.LoadSprite("Sprites/AKEmpty.png");

var MANFBBIR = Instance.GetComponent<AmmoUsageBehaviour>();
// fixing duplicate error
if (MANFBBIR == null) {
Instance.AddComponent<AmmoUsageBehaviour>();
MANFBBIR = Instance.GetComponent<AmmoUsageBehaviour>();
}
// end of fix 1
MANFBBIR.Mag = ModAPI.LoadSprite("Sprites/AKMag.png");
MANFBBIR.MagExtended = ModAPI.LoadSprite("Sprites/AKMagExtended.png");
MANFBBIR.Empty = ModAPI.LoadSprite("Sprites/AKEmpty.png");
MANFBBIR.Loaded = ModAPI.LoadSprite("Sprites/AKLoaded.png");
MANFBBIR.LoadedExtended = ModAPI.LoadSprite("Sprites/AKLoadedExtended.png");
MANFBBIR.AmmoID = 2; //Used for munutions
// fixing ammo count on load
if (MANFBBIR.ammoLoaded == "standard") {
MANFBBIR.MaxAmmo = 30;
}
else {
MANFBBIR.MaxAmmo = 45;
}
// end of fix 2

---

After 5 hours of studying C# (its just javascript on drugs), reading PPG mod documentation and fighting with the terrible code, I've found the potential fix for all of your problems:

Line 717 in TheEntireGodDamnScript.cs:
Write [SkipSerialisation]

Without it whole Behaviour gets saved causing it to duplicate all scripts on next spawn.

I haven't tested it for bugs but everything seems to be working.

(btw I'm gonna use this mod to add reloading to Catt's Cannons, I hope I got permission for that)