Last year, the German armed forces announced they would purchase Heckler and Koch’s MG-5 machine gun to finally replace a World War II-era weapon. The new machine gun should put the Bundeswehr’s existing weapons to shame—and make up for past failures. “Its main feature is that it is much more accurate than its predecessor,” German army colonel Christian Brandes told U.S. Army reporters at Yuma Proving Ground in Arizona during testing of the new gun on Oct. 14. The predecessor Brandes was referring to is the MG-3. That aging weapon is essentially just an upgrade of a machine gun Adolf...