Seems to be some debate about this. The argument, of course, is that the enemy would hear the distinct 'ping' and charge GI Joe who was now helpless because he supposedly had an empty rifle. Problem with this reasoning is that Joe had a buddy sitting next to him in the foxhole. I have a feeling this has taken on urban legend status, but I'm interested in hearing from anyone who has first-hand knowledge of whether this phenomenon actually caused the deaths of many US soldiers in WWII.