I've been present for their use, but not in semi-automatic or automatic weapons. Based on my observations, it would have offered a greatly muffled sound from the level of the shooting, giving the shooter more time prior to being discovered. That may be seconds, but in a situation like this that would have been sufficient to have ended many more human lives. If I am wrong, I accept that, but I do not sense that I am based on what I have read and witnessed.