How to add material detection to TurboFusion's gun script?

Basically, it detects what material you're firing at. So, if it's metal, diamond plate, or corroded metal, it changes the bullet hole texture to a dent. I'm having trouble with figuring this out. If someone can help me, thanks!! Also, if you shoot something that's a model, and it has a "Humanoid" in it, it makes a blood splat on that person or creature that was shot, and makes blood splats behind them. I'd like the wound texture to be different from the actual blood splat, as well.

Granite, slate, grass, brick, concrete, cobblestone, and pebbles, plastic, and smooth splastic share the same bullet hole texture. Ice and marble share the same texture. Sand has it's own texture. And metal, corroded metal, and diamond plate share the same same texture. Wood and wooden planks also share the same texture (which are splinters.) Also, if the part is invisible, no bullet holes show up.

--Bullet hole texture script (in the script named "Settings."

BulletHoles = true; --This is whether or not bullet holes will appear where you shot
	BulletHoleTexture = "http://www.roblox.com/asset/?id=190093197"; --This is the texture of the bullet hole
	BulletHoleSize = 1; --This is how big the bullet hole will be in studs
	BulletHoleVisibleTime = 12; --This is how long the bullet hole will be visible for
	BulletHoleDisappearTime = 1; --This is how long it will take for the bullet hole to disappear

--Part in the gun's main script that creates bullet holes on parts.

function CreateBulletHole(HitPos, HitObj)
	CreateShockwave(HitPos, 0.3, 0.2)
	local SurfaceCF = GetHitSurfaceCFrame(HitPos, HitObj)
	local SurfaceDir = CF(HitObj.CFrame.p, SurfaceCF.p)
	local SurfaceDist = SurfaceDir.lookVector * (HitObj.CFrame.p - SurfaceCF.p).magnitude / 2
	local SurfaceOffset = HitPos - SurfaceCF.p + SurfaceDist
	local SurfaceCFrame = SurfaceDir + SurfaceDist + SurfaceOffset
	local HitMark = Instance.new("Part")
	HitMark.BrickColor = BrickColor.new("Black")
	HitMark.Transparency = 1
	HitMark.Anchored = true
	HitMark.CanCollide = false
	HitMark.FormFactor = "Custom"
	HitMark.Size = VEC3(1, 1, 0.2)
	HitMark.TopSurface = 0
	HitMark.BottomSurface = 0
	local Mesh = Instance.new("BlockMesh")
	Mesh.Offset = VEC3(0, 0, -0.05)
	Mesh.Scale = VEC3(S.BulletHoleSize, S.BulletHoleSize, 0)
	Mesh.Parent = HitMark
	local Decal = Instance.new("Decal")
	Decal.Face = Enum.NormalId.Front
	Decal.Texture = S.BulletHoleTexture
	Decal.Parent = HitMark
	HitMark.Parent = Gun_Ignore
	HitMark.CFrame = SurfaceCFrame
	if (not HitObj.Anchored) then
		local Weld = Instance.new("Weld", HitMark)
		Weld.Part0 = HitObj
		Weld.Part1 = HitMark
		Weld.C0 = HitObj.CFrame:toObjectSpace(SurfaceCFrame)
		HitMark.Anchored = false
	end
	delay(S.BulletHoleVisibleTime, function()
		if S.BulletHoleDisappearTime > 0 then
			local X = 0
			while true do
				if X == 90 then break end
				if (not Selected) then break end
				local NewX = X + (1.5 / S.BulletHoleDisappearTime)
				X = (NewX > 90 and 90 or NewX)
				local Alpha = X / 90
				Decal.Transparency = NumLerp(0, 1, Alpha)
				RS:wait()
			end
			HitMark:Destroy()
		else
			HitMark:Destroy()
		end
	end)
end

To return a material you would use Enumerations.

function getMaterial(part)
if part.ClassName=="Part" then
return part.Material
end
end

if getMaterial(workspace.Part)==Enum.Material.Plastic then
print("Part was plastic")
end

This is a very simple detection script for you to use.

Read more on Enumerations go to this wiki article