Stabilizing the fire frequency

I've added onkeydown event listener to document, and when the event fires, I play an audio file. This audio file is a gun sound. If you tap the key once, it plays fine, but if you press and hold, the audio repeats incredibly fast. I've solved that with a simple playing condition check, but I have another problem. If I press and hold, only after the first shot, it sounds like the gun is firing repeatedly. For example, it goes like ta-tatatatata.

How can I fix my machine gun? Make it fire like tatatata.

Demo

---

var weapons = {
    aug : {
        audio   : "weapons/aug-1.wav",
        icon    : "e",
        key     : "A"
    }
};

function playAudio(file) {
    if (!playing) {
        var audio = new Audio(file);
        audio.play();
        playing = true;
        setTimeout(function() {
            playing = false;
        }, 100);
    }
}

document.onkeydown = function(e) {
    switch(e.keyCode) {
        case 65:
            playAudio(weapons.aug.audio);
            break;
    }
}