I was shooting across my chrono a few years back, when a guy set up about 8 bays over from me. He pulled out a nice rifle in one of the bigger medium magnums, complete with muzzle brake. When he started shooting his groups (I assume), every time he fired, my chrono display would change. I had on muffs, but had to put in plugs under the muffs to be able to stay on the firing line while he was shooting.