Bror Blix mentions the story in his book. He is having a G&T with a german called Udett alone with Cooper. Udett was wingcommander and flew with Hermann Göring and the Red Baron over Flandern(Belgium) when it when it took place. Udett explains they lost planes from rifle fire below and couldn`t understand how it could done. Cooper then explains he was one of the officers who brought their big game double rifles on the battlefield to see if they could shoot down german airplanes….and they could. The funny part of the story is ofcouse that Dick cooper and Udett had never met before sitting down and enjoying a Gin & tonic in africa and sharing their story.