Good point. I have it reliable authority that a large west coast police department had at least 2 NDs with slung firearms. In both cases, the long guns were on safe, originally, but contact with vest-mounted gear swiped off the safety. Sometime later, a careless finger or other piece of vest-mounted gear pressed the trigger. That's why ITTS teaches positive control of the slung firearm with at least one hand, at all times.