Didnt Patton claim that this was the "..best battle implement ever devised by man..."?
Ever the telltale "ping" of an empty rifle couldn't stop it's effectiveness.
Everyone has heard the sound made when one is empty, so the Gi's countered this by firing a shot, then taking a spare empty clip, and throwing it against their capon, to simulate the sound of an empty rifle. This would immediately get the Nazi's attention, having fooled them into thinking that the rifle was empty, Nazis would expose themselves only to be slaughtered by GI's weilding NON EMPTY Garand rifles
..pretty cool, huh?