How can I stop a gun from attacking players and only attack NPC's?

Hello Scripters! I want to edit the script in the AR kit gun so that it can only damage and kill NPC's, even if the NPC's have humanoids. The gun kit is here I am using the AR gun: https://www.roblox.com/library/3932803955/Auto-Rifle (Paste in broswer top bar as it wont work as a link for some reason.) The script that does damage is the WeaponsSystem. Get the gun kit and put it in studio to try and help me. I have tried to make it so that it says:

if target IsA Player then
--Do Damage

but it didnt work at all so can someone please help me. Please get the gun to understand how it is made and to get the full script(s). If anyone can help me, thankyou so much!!

I would recommend "labeling" all npcs here is a article on how to do that:

https://developer.roblox.com/en-us/api-reference/class/CollectionService

local CollectionService = game:GetService("CollectionService")

if CollectionService:HasTag(target, "NPC") then
	print("Don't Shoot")
	-- search for other targets