Can anyone help with this weapon Script?

Its meant to check for Ammo, and then If it has ammo fire, if it does not then wont fire, It works until you have no ammo, then when I add More It Breaks.

wait(5)
local tool = script.Parent
local user
local tip = tool.tip
local change = tool.Handle.change
local shot = tool.Handle.shot
local wide = tool.Handle.wide
local e = tool.button1
local q = tool.button2
local Damage = math.random(15,25)
local BonusDamage = math.random(5,15)
local mode = 1
local setting = 1
local reload = false

function onKeyDown(key,g)
	if key == "q" then
		change:Play()
		if mode == 1 then
			mode = 2
			g.Frame.stun.Image = "http://www.roblox.com/asset/?id=178375629"
			g.Frame.kill.Image = "http://www.roblox.com/asset/?id=178375645"
		elseif mode == 2 then
			mode = 1
			g.Frame.stun.Image = "http://www.roblox.com/asset/?id=178375645"
			g.Frame.kill.Image = "http://www.roblox.com/asset/?id=178375629"
		end
		--print(mode)
		q.BrickColor = BrickColor.new("Medium stone grey")
		wait()
		q.BrickColor = BrickColor.new("Dark stone grey")
	elseif key == "e" then
		change:Play()
		if setting == 1 then
			setting = 2
			g.Frame.beam.Image = "http://www.roblox.com/asset/?id=178375629"
			g.Frame.wide.Image = "http://www.roblox.com/asset/?id=178375645"
		elseif setting == 2 then
			setting = 1
			g.Frame.beam.Image = "http://www.roblox.com/asset/?id=178375645"
			g.Frame.wide.Image = "http://www.roblox.com/asset/?id=178375629"
		end
		--print(setting)
		e.BrickColor = BrickColor.new("Medium stone grey")
		wait()
		e.BrickColor = BrickColor.new("Dark stone grey")
	end
end

function Reset()
if script.Parent.Ammo.Value < 1 then reload = false	
end

function impact(hit,h)
	if mode == 1 then
		if hit.Parent:IsA("Hat") == false and hit.Parent:IsA("Tool") == false and hit.Parent:IsA("HopperBin") == false then
			h:TakeDamage(3/setting)			
			if hit.Parent:findFirstChild("stun") == nil then
				local s = script.stun:Clone()
				s.Parent = hit.Parent
				s.Disabled = false
				s.expose.Adornee = s.Parent.Torso
				s.expose.Script.Disabled = false
				h.WalkSpeed = 10
			end
		else
			h:TakeDamage(3/setting)
			if hit.Parent.Parent:findFirstChild("stun") == nil then
				local s = script.stun:Clone()
				s.Parent = hit.Parent.Parent
				s.Disabled = false
				s.expose.Adornee = s.Parent.Torso
				s.expose.Script.Disabled = false
				h.WalkSpeed = 10
			end
		end
	elseif mode == 2 then
		if hit.Parent:IsA("Hat") == false and hit.Parent:IsA("Tool") == false and hit.Parent:IsA("HopperBin") == false then
			if hit.Parent:findFirstChild("stun") == nil then
				h:TakeDamage(BonusDamage/setting)
			else
				h:TakeDamage(Damage/setting)
			end
		else
			if hit.Parent.Parent:findFirstChild("stun") == nil then
				h:TakeDamage(BonusDamage/setting)
			else
				h:TakeDamage(Damage/setting)
			end
		end
	end
end

tool.Equipped:connect(function(mouse)
	local gui = script.PhaserGui
	user = tool.Parent
	local g = gui:Clone()
	g.Parent = game.Players:GetPlayerFromCharacter(user).PlayerGui
	mouse.Button1Down:connect(function()
		
		if user.Humanoid.Health > 1 then
			if setting == 1 then
				if script.Parent.Ammo.Value < 1 then reload = true Reset() return
				elseif reload == false then
					shot:Play()
					script.Parent.Ammo.Value = script.Parent.Ammo.Value - 1
					reload = true
					local r = Ray.new(tip.CFrame.p, (mouse.Hit.p - tip.CFrame.p).unit*300)
					local hit,position = game.Workspace:FindPartOnRay(r, user)
					local h = hit and hit.Parent and hit.Parent:findFirstChild("Humanoid")
					if hit ~= nil and hit.Parent.Parent:findFirstChild("Humanoid") and hit.Parent.Parent ~= workspace then
						h = hit.Parent.Parent:findFirstChild("Humanoid")
					end
					if h then
						impact(hit,h)
					end
					local distance = (position - tip.CFrame.p).magnitude
					local rp = Instance.new("Part", workspace)
					rp.Name = "RayPart"
					rp.BrickColor = BrickColor.new("Bright orange")
					rp.Transparency = 0
					rp.Anchored = true
					rp.CanCollide = false
					rp.TopSurface = Enum.SurfaceType.Smooth
					rp.BottomSurface = Enum.SurfaceType.Smooth
					rp.formFactor = Enum.FormFactor.Custom
					rp.Size = Vector3.new(0.2, 0.2, distance)
					rp.CFrame = CFrame.new(position, tip.CFrame.p) * CFrame.new(0, 0, -distance/2)
					local m = Instance.new("BlockMesh", rp)
					m.Scale = Vector3.new(0.25,0.25,1)
					local e = Instance.new("Part", workspace)
					e.CFrame = CFrame.new(position)
					e.Transparency = 1
					e.Size = Vector3.new(1,1,1)
					local f = Instance.new("Fire",e)
					local pl = Instance.new("PointLight",e)
					local st = rp:Clone()
					st.Parent = rp
					if mode == 1 then
						st.BrickColor = BrickColor.new("Bright yellow")
					end
					st.Mesh.Scale = Vector3.new(0.5,0.5,1)
					st.Transparency = 0.75
					game.Debris:AddItem(rp,0.25)
					game.Debris:AddItem(e,0.25)
					wait(0.5)
					reload = false
				end
			elseif setting == 2 then
				if script.Parent.Ammo.Value <500 then reload = true return
				elseif reload == false then
					wide:Play()
					script.Parent.Ammo.Value = script.Parent.Ammo.Value - 500
					reload = true
					for i = -130,130 do
						local r = Ray.new(tip.CFrame.p, ((mouse.Hit*CFrame.new(Vector3.new((0.1*i),0,0)).p) - tip.CFrame.p).unit*100)
						local hit,position = game.Workspace:FindPartOnRay(r, user)
						local h = hit and hit.Parent and hit.Parent:findFirstChild("Humanoid")
						if h then
							impact(hit,h)
						end
						local distance = (position - tip.CFrame.p).magnitude
						if i == 0 then
							local rp = Instance.new("Part", user)
							rp.Name = "RayPart"
							rp.BrickColor = BrickColor.new("Bright orange")
							rp.Transparency = 0
							rp.Anchored = true
							rp.CanCollide = false
							rp.TopSurface = Enum.SurfaceType.Smooth
							rp.BottomSurface = Enum.SurfaceType.Smooth
							rp.formFactor = Enum.FormFactor.Custom
							rp.Size = Vector3.new(0.2, 0.2, distance)
							rp.CFrame = CFrame.new(position, tip.CFrame.p) * CFrame.new(0, 0, -distance/2) * CFrame.Angles(300,0,0)
							local m = Instance.new("SpecialMesh", rp)
							m.MeshType = "FileMesh"
							m.MeshId = "http://www.roblox.com/asset/?id=1033714"
							m.Scale = Vector3.new(25,1.275*distance,0.001)
							local st = rp:Clone()
							st.Parent = rp
							st.Mesh.Scale = Vector3.new(25.5,(1.275*distance)+0.5,0.101)
							st.Transparency = 0.75
							if mode == 1 then
								st.BrickColor = BrickColor.new("Bright yellow")
							end
							game.Debris:AddItem(rp,0.5)
						end
					end
					wait(1.5)
					reload = false
				end
			end
		end
	end)
	mouse.KeyDown:connect(function(string) onKeyDown(string,g) end)
end)

tool.Unequipped:connect(function ()
	if tool.Parent.Parent:FindFirstChild("PlayerGui") ~= nil and tool.Parent.Parent:FindFirstChild("PlayerGui"):FindFirstChild("PhaserGui") ~= nil then
		tool.Parent.Parent.PlayerGui.PhaserGui:Destroy()
	end
	
end)