"His hit rate was significantly higher than the norm. It seemed that they were not even willing to change things after that."
Was that based on a verifiable test or a report? the problem was , like AA gunners, any enemy aircraft that was hit was claimed by everyone in sight
The RCAF had belly turrets on their bombers but I never saw any figures to prove or disprove that they lost less aircraft because of it - the attack from underneath being very common and very lethal