Weapon Ammo counter not working?

Hello, Ive been working on a custom weapon for my game and have come across this peculiar issue. I had previous success counting down the ammunition by using a separate localscript from the raycasting/main one, but it fails to disable the raycasting script for some reason so I am trying to put the counter in the raycasting script instead.

When printing "Ammo", it always shows up as 12, which means its not updating the value for some reason?

local ammo = 12
local cooldown = 1.5

tool.Equipped:connect(function(mouse)
    user = tool.Parent 
mouse.Button1Down:connect(function()
        if ammo >= 1 then
        print(ammo)
        local ray = Ray.new(tool.Barrel.CFrame.p, (mouse.Hit.p - tool.Barrel.CFrame.p).unit*300)
        local hit, position = game.Workspace:FindPartOnRay(ray, user)
        local distance = (position - tool.Barrel.CFrame.p).magnitude
        local rayPart = Instance.new("Part", user)
        rayPart.Name          = "RayPart"
        rayPart.BrickColor    = BrickColor.new("Neon orange")
        rayPart.Material      = Enum.Material.Neon
        rayPart.Transparency  = 0
        rayPart.Anchored      = true
        rayPart.CanCollide    = false
        rayPart.TopSurface    = Enum.SurfaceType.Smooth
        rayPart.BottomSurface = Enum.SurfaceType.Smooth
        rayPart.formFactor    = Enum.FormFactor.Custom
        rayPart.Size          = Vector3.new(0.2, 0.2, distance)
        rayPart.CFrame        = CFrame.new(position, tool.Barrel.CFrame.p) * CFrame.new(0, 0, -distance/2)

        local SpawnPos = script.Parent.Parent.PrimaryPart
        local Fire = script.Parent.Handle.Fire
        local Reload = script.Parent.Handle.Load
        local stinger = script.Parent.Stinger
        local humanoid = hit and hit.Parent and hit.Parent:FindFirstChild("Humanoid")
        script.Disabled = true

        if humanoid then
                ammo = (ammo - 1)
                tool.Name = ammo
            Fire:Play()
            stinger.Transparency = 1
            Remote:FireServer(humanoid, SpawnPos)
            game.Debris:AddItem(rayPart, 0.02)
            local reloading = script.Parent.Parent.Humanoid:LoadAnimation(script.Reload)
            reloading:Play()
            wait(cooldown)
            Reload:Play()
        else 
            script.Parent.Handle.Miss:Play()
            stinger.Sparks.Enabled = true
            wait(.1)
            stinger.Sparks.Enabled = false
        end 
        game.Debris:AddItem(rayPart, 0.02)
        script.Parent.Stinger.Transparency = 0
            script.Disabled = false
            end
        end)
end)

Im not sure what Im doing wrong. I also only want it to count down if it hits a humanoid and deals damage, which is why the equation is where it is.