Heck, my Pact timer picks up 3-4 shots for every one that's actually fired when I'm ROing indoor matches due to all of the echoes off of the hard walls. Ultimately, that just means that everybody's recorded time on every stage is like + 0.25 second from reality, but since it's the same for everyone, it kind of doesn't matter too much. If you were trying to use a timer with people shooting on other lanes, though, yeah, none of them will work well except for the ShotMaxx watch, which has some sort of inertial sensor that it can use instead of the audio.