News to me. The Zero machine guns were chambered for the .303 British cartridge. I always through they were 7.7 Arisaka The Imperial Japanese Navy (and Imperial Japanese Navy Air Service) never shared weapons or ammunition with the army, instead adopting the 7.7x56mmR, a direct copy of the .303 British round 7.7×58mm Arisaka - Wikipedia Type 97 aircraft machine gun - Wikipedia
