How to make guns fire at fast speeds in games?

so im trying to find a way to have guns that fire at very fast speeds. However it doesnt work for the most part. But if you do a wierd glitch where to tap really fast it does.

local RunService = game:GetService("RunService")

local function functionToBind() 
	if num2 >= 2 then
	if Firing then
FireEffect()
	num2 = 0
		end
	else
		num2 = num2 + 1
		end
end

-- Bind the function above to the binding named "tempBinding"
RunService:BindToRenderStep("tempBinding", 1, functionToBind)