The Type 99 cannon suffered from relatively low muzzle velocity and rate of fire compared to other 20mm cannons but the trade off was an extremely light cannon that did not hinder flight performance of the IJN's fighter aircraft. The close economic and political ties between the IJN and Dai Nihon Heiki KK ensured that the latter had little competition.
The Type 99 cannon was inferior in terms of muzzle velocity and rate of fire compared to other 20mm cannons, but it excelled in being lightweight. This allowed it not to affect the flight performance of IJN fighter aircraft. The close economic and political ties between the IJN and Dai Nihon Heiki KK ensured that the latter had little competition.