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)