How do I make this rapid fire with UristMcSpark's pistol?

I want to try making the gun script, automatic (rapid). But the problem is I don't know how to trigger it properly. Look down for examples.

Here's an brief-example of what I did so far:

mouse.Button1Down:connect(function()
    mouse.Button1Up:connect(function()
        game.ReplicatedStorage.ROBLOX_PistolFireEvent:FireServer(mouse.Hit.p)
    end)

Then here's my next one, it works fine but it shoots not automatic but pistol type. Where you have to spam click.

mouse.Button1Down:connect(function()
        game.ReplicatedStorage.ROBLOX_PistolFireEvent:FireServer(mouse.Hit.p)
    end)

I had to use UristMcSpark pistol because I'm not familar with gun-scripting, rather than GUI scripting.