Type 99 Mark 1 file photo [27144]

Type 99 Mark 1 Aircraft Autocannon

Country of OriginJapan
TypeAircraft Autocannon
Caliber20.000 mm
Length1,330.000 mm
Weight23.000 kg
Ammunition Weight0.13 kg
Rate of Fire520 rounds/min
Muzzle Velocity600 m/s



This article deals with a Japanese aircraft autocannon variant of the Oerlikon 20-millimeter design. For other aircraft autocannon variants, please see Type 99 Mark 2 and 20 mm MG-FF Oerlikon. For the design's land and ship-based anti-aircraft applications, please see 20 mm Oerlikon anti-aircraft.

Type 99 Mark 1
existing 353

In 1935, the Japanese Navy began searching for 20-millimeter autocannons/machine guns to arm future fighter aircraft. It settled on the designs by the Swiss firm Oerlikon in 1937. A newly formed company, Dai Nihon Heiki KK, established by retired Navy officers, purchased two licenses from Oerlikon, one for Oerlikon FF and another for Oerlikon FFL, to produce Type 99 Mark 1 Machine Guns (Kyukyu Shiki Ichigo Kizyu) and Type 99 Mark 2 Machine Guns (Kyukyu Shiki Nigo Kizyu), respectively.

Type 99 Mark 1 machine guns were used in both fixed and flexible applications. The fixed installation application was developed first, mounted in the wings of the early variants of A6M Zero fighters. Each weapon was fed by a 60-round drum. The flexible application was first seen on G3M bombers. The drum limitation was later addressed in the 4th variant of the Type Mark 1, which introduced belt-feeding. Mark 1 weapons fired a smaller cartridge than their Mark 2 counterparts, and enjoyed a higher rate of fire, although they had a lower muzzle velocity. Toward the end of the war, they slowly fell out of favor, and were slowly overtaken by Mark 2 machine guns.

Source: Wikipedia ww2dbase


Japanese Navy Type 99 Mark 1 (top) and Type 99 Mark 2 (bottom) aircraft machine guns, circa 1945

Did you enjoy this article? Please consider supporting us on Patreon. Even $1 per month will go a long way! Thank you.

Share this article with your friends:

 Facebook  Reddit
 Twitter  Digg
 Google+  Delicious

Stay updated with WW2DB:

 RSS Feeds

Posting Your Comments on this Topic

Your Name
Your Email
 Your email will not be published
Comment Type
Your Comments
Security Code


Note: We hope that visitor conversations at WW2DB will be constructive and thought-provoking. Please refrain from using strong language. HTML tags are not allowed. Your IP address will be tracked even if you remain anonymous. WW2DB site administrators reserve the right to moderate, censor, and/or remove any comment. All comment submissions will become the property of WW2DB.

Search WW2DB & Partner Sites
Type 99 Mark 1 Aircraft Autocannon Photo Gallery
Japanese Navy Type 99 Mark 1 (top) and Type 99 Mark 2 (bottom) aircraft machine guns, circa 1945

Famous WW2 Quote
"An appeaser is one who feeds a crocodile, hoping it will eat him last."

Winston Churchill