I know not to take anything on TV or the movies as valid, but on an episode of the series "Counterpart" on STARZ TV, a character empties a regular water bottle, stuffs a cloth into the bottle, then hold it over the muzzle of the semi auto as he fires a round into a nearby individual. Of course on the show the sound is almost totally eliminated, but it made me wonder how much noise suppression this would actually provide. I might just try it myself at my next visit to the range, but wondered what you might think about this.