Why does my gun fire in full auto twice if I press down twice?

My username is Yeeterbo_i and I am a beginner scripter. Recently, I have been trying to make my own non raycast gun for future games. However, I just ran into a problem while trying to make it full auto. If I click twice before my gun fires again, my gun instead of going pew (wait 0.1) pew (wait 0.1) pew, it goes like this: pew pew (wait 0.1) pew pew (wait 0.1) pew pew.

If you need the script for my gun, its down here.

-- This is an extremely simple non-raycasting pistol made by Yeeterbo_i. It is basically a fancy damage brick teleporter.
--Variables
input_service = game:GetService("UserInputService")
local tool = script.Parent
local player = game:GetService("Players").LocalPlayer
local mouse = player:GetMouse()
local ammo = 12
local mag = 12
local CanReload = true
local reload = false
local Firing = false
tool.Equipped:Connect(function(mouse)


 mouse.Button1Down:Connect(function()
    Firing = true
    while ammo > 0 and reload == false and Firing == true  do --Checks for ammo and if player is currently reloading

        --Visual effects
        tool.FireDecalHolder.FireDecal1.Transparency = 0
        tool.FireDecalHolder.FireDecal2.Transparency = 0

    tool.SlideBack.Transparency = 0
        tool.Slide.Transparency = 1
        --Audio effect
        tool.FireSound.TimePosition = 0
        tool.FireSound.Playing = true

        --Creating damage brick
    local oof = game.Workspace.Oofpart:Clone()
        oof.BrickColor = BrickColor.Black()
        oof.Size = Vector3.new(0.7,0.7,0.7)
        oof.Position = mouse.Hit.p
        oof.Transparency = 0
        oof.Anchored = true
        oof.CanCollide = false
        oof.Parent = workspace

    game:GetService("Debris"):AddItem(oof, 0.001)--Removing block
    ammo = ammo - 1 --Removing ammo from mag
    wait(0.05)

    --Removing visual effects
    tool.FireDecalHolder.FireDecal1.Transparency = 1
        tool.FireDecalHolder.FireDecal2.Transparency = 1

    tool.SlideBack.Transparency = 1
        tool.Slide.Transparency = 0
        wait(0.1)--ROF
    end
if ammo < 1 then
    tool.EmptySound.TimePosition = 0
    tool.EmptySound.Playing = true
        end
    end)
end)
mouse.Button1Up:Connect(function()
    Firing = false
end)
 function PressedR(key)
    if key == "r" and CanReload == true then
    CanReload = false
    script.Parent.ReloadSound.Playing = true
            print("oof")
        reload = true
        wait(1.5)
        reload = false
        ammo = mag
    CanReload = true
    end
end

mouse.KeyDown:Connect(PressedR)