Why doesn't my weld script position the hat correctly?

My weld script is supposed to weld the gasmask to the player positioning it over the player. It's supposed to be just like a hat. Instead it decides that it's okay to position itself behind/in front of my player when I need it to be in the exact location of the players head position. What is going on, and how can I fix this?

local hat= script.GasMask local weld

function weld(h,c)
	local hat2= h:clone()
	hat2.Parent= c
	local head = c:FindFirstChild("Head")
	if head ~= nil then
	local p
	for _,v in pairs(hat2:GetChildren()) do
		if v:IsA("Part") or v:IsA("UnionOperation") or v:IsA("MeshPart") then
			local weld= Instance.new("Weld")
			weld.Parent= head
			local core= v.Parent:FindFirstChild("Core")
			if core ~= nil then
				weld.Part0 = head
				weld.Part1 = v
				local lol = CFrame.new(head.Position.X,head.Position.Y,head.Position.Z)
				weld.C1 = v.CFrame:inverse()*lol
				p=v
			end
			v.Anchored= false
		end
	end
		if p ~= nil then
			local gM = p.Parent
			if gM:IsA("Model") then
				gM:SetPrimaryPartCFrame(CFrame.new(head.Position.X,head.Position.Y,head.Position.Z))
			end
		end
	end
end

function clean(c)
	for _,v in pairs(c:GetChildren()) do
		if v:IsA("Hat") or v:IsA("Accessory") then
			v:Destroy()
		end
	end
end

game.Players.PlayerAdded:Connect(function(plr)
	repeat wait() until plr.Character
	wait(3)
		clean(plr.Character)
		weld(hat,plr.Character)
	plr.CharacterAdded:Connect(function(char)
		clean(char)
		weld(hat,char)
	end)
end)