Changing attachment stats

[MetagrossJK2]

Hello. I was trying to mess around with the AMCAR, making a simple mod to edit its stats. But then i wanted to edit its attachments stats, and i dont know how xD I don't have any idea of modding, i just used another mod as a template and started adding things.

Anyways, what i want is, in this case, edit the quad-stacked magazine stats so it gives less extra ammo, more damage, etc, but only for the AMCAR. So, for other weapons that share this attachment, like the CAR-4, it should have its original stats.

I tried this:

local old_init = WeaponTweakData.init

function WeaponTweakData:init(tweak_data)
    old_init(self, tweak_data)

self.amcar.stats.concealment = 29
self.amcar.CLIP_AMMO_MAX = 10
self.amcar.NR_CLIPS_MAX = 15
self.amcar.AMMO_MAX = self.amcar.CLIP_AMMO_MAX * self.amcar.NR_CLIPS_MAX

self.amcar.wpn_fps_ass_amcar.parts.wpn_fps_upg_m4_m_quad.stats = {
	damage = 15
	recoil = -8
	spread = -4
	extra_ammo = 5
	concealment = -5
}

end

So i tried something like self."weapon"."factory".parts."part".stats = {}, but unfortunately, when i include that last block, the whole mod stops working. If i remove it, the rest of the script works fine. I assume i'm making a noob mistake, but i couldn't find anything to be able to know what it is, so here i am xD

HALP MI PLS