How to make this Filtering Enabled?

originalAmmo = script.Parent.Ammo.Value
m = Instance.new("Message")

function computeDirection(vec)
    local lenSquared = vec.magnitude^2
    local invSqrt = 1 / math.sqrt(lenSquared)
    return Vector3.new(vec.x * invSqrt, vec.y * invSqrt, vec.z * invSqrt)
end



function updateAmmo()
    m.Text = " "
    --for i = 1,script.Parent.Ammo.Value do
    --  m.Text = m.Text .. "|"
    --end
    --for i = 1, (originalAmmo - script.Parent.Ammo.Value) do
    --  m.Text = m.Text .. " "
    --end
    m.Text = m.Text .. " " .. script.Parent.Ammo.Value.. "/10"
end


function fire(v)
    for i = 1,1 do
        script.Parent.Handle.Fire:play()
        script.Parent.Ammo.Value = script.Parent.Ammo.Value - 1
        updateAmmo()

        local dir = v - script.Parent["Handle"].Position
        dir = computeDirection(dir)

        local pos = script.Parent["Handle"].Position + (dir * 6)

        local p = Instance.new("Part")
        p.Name = "Projectile"
        p.CFrame = CFrame.new(pos, pos + dir)
        p.BrickColor = BrickColor.new(21)
        p.Reflectance = 0.1
        p.Velocity = (script.Parent.Parent["Head"].Position - v).unit * -150
        p.Size = Vector3.new(1, 0.4, 1)
        p.formFactor = 2

        local mesh = script.Parent.Mesh:clone()
        mesh.Parent = p

        local upforce = Instance.new("BodyForce")
        upforce.force = Vector3.new(0, p:GetMass() * 196, 0)
        upforce.Parent = p

        local creator = Instance.new("ObjectValue")
        creator.Name = "creator"
        creator.Value = game.Players:GetPlayerFromCharacter(script.Parent.Parent)
        creator.Parent = p

        local s = script.Parent["ProjectileScript"]:Clone()
        s.Disabled = false
        s.Parent = p
        p.Parent = game.Workspace
        wait(0)
    end
end


function onActivated()
    if script.Parent.Enabled == true then
        script.Parent.Enabled = false
        if script.Parent.Ammo.Value > 0 then
            fire(script.Parent.Parent["Humanoid"].TargetPoint)
        else
            script.Parent.Enabled = false
            script.Parent.Handle.Reload:play()
            m.Text = "Reloading."
            for i =1,5 do
                wait(0.3)
                m.Text = m.Text .. "."
            end
            script.Parent.Ammo.Value = originalAmmo
            updateAmmo()
            script.Parent.Enabled = true
        end
        wait(0.1)
        script.Parent.Enabled = true
    end
end


function onEquipped()
    local p = game.Players:GetChildren()
    for i = 1,#p do
        if p[i].Character == script.Parent.Parent then
            m.Parent = p[i]
        end
    end
    updateAmmo()
end

function onUnequipped()
    m.Parent = nil
end


script.Parent.Activated:connect(onActivated)
script.Parent.Equipped:connect(onEquipped)
script.Parent.Unequipped:connect(onUnequipped)