Original Item: Only One Available. This is an extraordinarily scarce piece, a Japanese Type 99 Model 1 Mark 3 20mm Autocannon used as the larger caliber wing cannon aboard the aboard the A6M Zero, one of the most recognizable and infamous aircraft ever designed.

It is constructed from all original parts on an original BATF compliant non-firing display receiver, making this a 100% legal display gun. An 8 inch section of solid steel cylindrical bar stock has been inserted between two severed sections of the receiver, and the right side of the receiver was cut, removing another 3" section. So in total, 11" of the original receiver has been totally removed and discarded over two locations. The barrel is still live, albeit rusted. The bolt is inside of the gun and is welded in place. This is an incredible example, and as far as we know, this is the first example to ever come to market.

The Mitsubishi A6M "Zero" is a long-range fighter aircraft formerly manufactured by Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. The A6M was designated as the Mitsubishi Navy Type 0 carrier fighter, or the Mitsubishi A6M Rei-sen. The A6M was usually referred to by its pilots as the Reisen, "0" being the last digit of the imperial year 2600 (1940) when it entered service with the Imperial Navy. The official Allied reporting name was "Zeke", although the use of the name "Zero" (from Type 0) was used colloquially by the Allies as well.

The Zero is now considered the most capable carrier-based fighter in the world when it was introduced early in World War II, combining excellent maneuverability and very long range. The Imperial Japanese Navy Air Service (IJNAS) also frequently used it as a land-based fighter.

This phenomenal example is offered in lovely display condition, with a myriad of markings across several different pieces. There are two serial numbers we can find on different parts of the gun, 1389 and 1396. Considering how close the numbers are, we can assume that the replaced parts may have been replaced at a depot. We tried to transcribe the numerous kanji on the gun, which are highlighted yellow, but were only able to get the first two lines with accuracy:

惠 式 二 〇 粍 固 定 梭 銃 一 型 改 一    1389

昭 和 16 年 12 月

This roughly translates to the following, with the last line added by a photo translation program:

Keishiki 20mm Heavy Machine Gun Type 1 1389

December 1941

Dai Nihon Heiki KK Weapons Co., Ltd. Tomioka Weapons Factory

To produce the Oerlikon guns, a group of retired Navy admirals created a new arms manufacturing company, the Dai Nihon Heiki KK. In 1939 this started producing a Japanese version of the FF, initially known as the Type E (because the Japanese transliteration of Oerlikon was Erikon) but from late 1939 onwards formally known as the Type 99 Mark 1.

The gun measures roughly 52” long, weighs roughly 52 pounds, and from what we can tell, never had a mount, being attached to the Zero as it is. Overall the condition is truly fantastic, with the majority of the original finish still present on most parts of the gun. We did check the barrel is still, and it has not been deactivated, but the interior is very rusted. There doesn’t appear to be much rust elsewhere, however, and the entire gun has a lovely aged patina. The gun would display very well as is, but could also do with a custom mount or display.

This is a phenomenal piece of WWII & aviation history, the first Japanese aircraft gun we have ever been able to offer, and likely the last! Don’t miss out on this one-of-a-kind piece, sure to become the centerpiece of any collection.

The Type 99 was the standard cannon on Japanese naval aircraft throughout the war, appearing in both fixed and flexible variants. It was based on the Oerlikon, for which the Japanese had negotiated a manufacturing license in 1936, but it was continually improved and refined. Early marks were known simply as E-shiki ("Oerlikon Type") guns, and it was not until 1941 and 1942 that the Model 1 and Model 2 were so designated. As with all Oerlikon variants, the Type 99 action was blowback with advanced primer ignition.

The Type 99 was not an outstanding weapon. Although its APIB action made the Type 99 one of the lightest aircraft cannon of the Second World War, suitable for the equally light Japanese Navy airframes, this came at the cost of a low muzzle velocity and rate of fire. The Type 99 was inferior to the Japanese Army's excellent Ho-5 cannon, which used a short recoil action, in every respect except overall weight. However, with the A6M "Zero" under design at the time that the Type 99 was adopted, weight was the preeminent consideration. It did not help that there was practically no cooperation between the Army and Navy on weapons systems and that the manufacturer of the Type 99, the Tomioka Weapons Works, had been set up by retired Navy officers.

Because it fired a bigger cartridge than the Type 99 Mark 1, the Type 99 Mark 2 had a higher muzzle velocity but a lower rate of fire, and was heavier. In the first years of the war the IJN preferred the Type 99 Mark 1, and it did not operationally use the Type 99 Mark 2 until 1942. Towards the end of the war it developed a preference for installing the Type 99 Mark 2, presumably to counter the improving performance and ruggedness of US combat aircraft. 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 Model 1 was based on the Oerlikon FF and came in both fixed and flexible marks. Early models were fed from 60-round drums, but by 1942 this was replaced with a 100-round drum.  The Model 1 Mark 4 was belt-fed and had a slightly faster rate of fire than the other marks. All marks had rather low muzzle velocities, which initially made them unpopular with aircrew.

In early combat operations, the Zero gained a legendary reputation as a dogfighter, achieving an outstanding kill ratio of 12 to 1, but by mid-1942 a combination of new tactics and the introduction of better equipment enabled Allied pilots to engage the Zero on generally equal terms. By 1943, due to inherent design weaknesses, such as a lack of hydraulic flaps and rudder rendering it extremely unmaneuverable at high speeds, and an inability to equip it with a more powerful aircraft engine, the Zero gradually became less effective against newer Allied fighters. By 1944, with opposing Allied fighters approaching its levels of maneuverability and consistently exceeding its firepower, armor, and speed, the A6M had largely become outdated as a fighter aircraft. However, as design delays and production difficulties hampered the introduction of newer Japanese aircraft models, the Zero continued to serve in a front line role until the end of the war in the Pacific. During the final phases, it was also adapted for use in kamikaze operations. Japan produced more Zeros than any other model of combat aircraft during the war.