Help with a material-based bullet hole system with ACS 1.7?

Hello, I am currently working on a custom version of ACS 1.7 and I wish to make a material-based bullethole system, I already have the basics of it so, when you shoot, it creates a bullethole on whatever part the bullet hit. Now, what I need is for it to be material-based, so basically, different bulletholes depending on the material of the part that the bullet hit.

The lines for this system to work are:

local default_bulletholes = {
	"4117124202";
	"4117124881";
	"4117125609";
	"4117126706";
	"4117127411";
}

and

	Evt.Hit:FireAllClients(Player, Position, HitPart, Normal, Material, Settings)
			local a = Instance.new("Part", BulletModel)
		a.FormFactor = "Custom"
		a.TopSurface = 0
		a.BottomSurface = 0
		a.Transparency = 1
		a.CanCollide = false
		a.Size = Vector3.new(0.5, 0, 0.5)
		a.CFrame = 	CFrame.new(Position,Position-Normal) * CFrame.Angles(90*math.pi/180,math.random(0,360)*math.pi/180,0)
		a.BrickColor = BrickColor.new("Really black")
		a.Material = Enum.Material.Air
		
		local b = Instance.new('WeldConstraint')
		b.Parent = a
		b.Part0 = a
		b.Part1 = HitPart
	
		local c = Instance.new("Decal", a)
		c.Texture = "rbxassetid://"..default_bulletholes[math.random(1,5)]
		c.Face = "Top"
--		c.Transparency = 0
		
		local d = Instance.new("PointLight", a)
		d.Color = Color3.new(0, 0, 0)
		d.Range = 0
		d.Shadows = true
		
		local e = Instance.new("Weld")
		e.Part0 = a
		e.Part1 = HitPart	

Some help would be extremely appreciated.

My discord: krypto#0514

In the default_bulletholes table, name each index the specific Material you want it to be used on.

For example:

local default_bulletholes = {}
default_bulletholes["Enum.Material.Plastic"] = whateverIdYouUseForPlastic

Then on line 19 of the second part, instead of math.random() do tostring(HitPart.Material).