My Weld Script is not Welding Armor "Perfectly" ?

Hello, I have Weld script that activates when the player picks certain item in the inventory. But when it copies the armor (Model) from the replicated storage and into the player I get a glitchy result. I hope you guys can help me out:

!Glitchy armor

local function weld(a,b)
    local w = Instance.new("ManualWeld", b)
    w.Name = a.Name.."_Weld_"..b.Name
    w.C0 = a.CFrame:inverse() * b.CFrame
    w.Part0 = a
    w.Part1 = b
end


local function weldModel(item_model, char)
    for i,v in pairs(item_model:GetChildren()) do
        if v:IsA("BasePart") or v:IsA("UnionOperation") or v:IsA("MeshPart") then
            local weldTo = char:FindFirstChild(v.Name)
            if weldTo then
                weld(v, weldTo)
            end
            v.Anchored = false 
        end
    end
end


_G.EquipItem = function(char)
    local item = game.ReplicatedStorage.Items:FindFirstChild(item_name)
    if item then
        if char:findFirstChild(item_name) then
            char:findFirstChild(item_name):Destroy()
        end
        for i,v in pairs(item:getChildren()) do
            if v:IsA("Model") then
                local item_model = v:Clone()
                item_model.Parent = char
                item_model:SetPrimaryPartCFrame(char.Head.CFrame)
                weldModel(item_model,char)
            end
        end
    end
end