How to rotate a part to face a brick?

Alright, I already know how to do it, but I have a weird issue when I rotate the brick to face the part in question. The video of the problem is here: https://youtu.be/dgF7W9D8kEY The problem is that the part I want to turn moves off the base of the turret which looks really bad. How could I fix it? The script is as follows:

function FindClosestPerson()
    for _,v in pairs(game.Players:GetChildren()) do
        if v.Character:FindFirstChild("Torso") ~= nil and v.Character:FindFirstChild("Humanoid") ~= nil and v.Character.Humanoid.Health > 0 then
            if (v.Character.Torso.Position - script.Parent.Union.Position).magnitude <= 20 then
                if v:GetRankInGroup(2874380) < 255 then
                return v.Character.Torso
        end
            else
                return nil
    end 
    end
    end
    end



function NoTarget()
    script.Parent:SetPrimaryPartCFrame(script.Parent.Part.CFrame * CFrame.fromEulerAnglesXYZ(0,0.01,0))
end

function Aim(TargetTorso)
    script.Parent.Union.CFrame = CFrame.new(script.Parent.Union.CFrame.p,TargetTorso.CFrame.p)
end

while true do
    local TargetTorso = FindClosestPerson()
    wait()
    print(TargetTorso)
    if TargetTorso == nil then NoTarget()
    else
        Aim(TargetTorso)
    end
    end