The Type 1 machine gun ( signifying its year of adoption, 1941) was a Japanese aircraft-mounted heavy machine gun widely used during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. It was also known as the Ho-103 in general use. The weapon itself was largely based on the American .50-caliber (12.7 mm)

M2 Browning The M2 machine gun or Browning .50-caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed near the end of World War I by John Browning. While similar to Browning's M1919 Browning machine gun, which was chambered ...

heavy machine gun, while the design of its ammunition was initially based on various Italian Breda-SAFAT 12.7 mm rounds. Japanese-designed and produced rounds eventually largely replaced these imported rounds. The Ho-103 achieved a slightly higher rate of fire (RoF) than the contemporary aircraft-mounted M2 Browning machine gun (AN/M2) by using the smaller, lower velocity semi-rimmed Breda-SAFAT 12.7 mm cartridge. The round was intermediate in length (88 mm) between the WWII German 13 mm calibre MG 131's ‘short’ 64 mm cartridge, and the ‘long’ 99 mm cartridge of the

. A high RoF was very desirable among aircraft weaponry; with the ever-increasing speeds of fighters, the window to score hits grew smaller and smaller. Thus, a higher RoF provided a greater density of fire and therefore a greater chance to hit. The compromise of a shorter cartridge to achieve this had drawbacks: Ho-103 rounds had a shorter maximum and effective range, as well as a lower velocity than their M2 Browning counterparts. To compensate for the mild to moderate loss in performance, the gun was frequently loaded with high-explosive incendiary (HEI) rounds. The Italian Breda-SAFAT HEI ammunition was initially copied as the fuzed Ma 103 round, until the fuzeless Ma 102 round was developed, carrying over double the high explosive content of the Ma 103.

Ammunition

The Ho-103 used a wide variety of ammunition; Most was produced in Japan, but some was imported from

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

(such ammunition was identical to that used in Breda-SAFAT HMGs). Types of ammunition used by the Ho-103 include: *

Ball A ball is a round object (usually spherical, but sometimes ovoid) with several uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for s ...

(full metal jacket), marked with a pink or red seal around the casemouth. * Armor piercing (AP) of Italian origin, marked with a black tip. *Armour piercing tracer (AP-T) with red tracer, marked with a pink tip and green and white seal around the casemouth. *AP-T with brighter-burning, longer-lasting red tracer, uncolored tip and black seal around the casemouth. *AP-T with white tracer, uncolored tip and green and white seal around the casemouth. *''Fuzed'' high-explosive incendiary (HEI) of Italian origin, its body painted blue or red. Contained of

PETN Pentaerythritol tetranitrate (PETN), also known as PENT, pentyl, PENTA (''ПЕНТА'', primarily in Russian), TEN (tetraeritrit nitrate), corpent, or penthrite (or, rarely and primarily in German, as ''nitropenta''), is an explosive material. ...

and incendiary composition. *Ma 103 ''fuzed'' HEI, marked with a white seal around the casemouth. Contained of

RDX RDX (Research Department Explosive or Royal Demolition Explosive) or hexogen, among other names, is an organic compound with the formula (CH2N2O2)3. It is white, odorless, and tasteless, widely used as an explosive. Chemically, it is classified ...

and incendiary composition. *Ma 102 ''fuzeless'' HEI, marked with a dark purple seal around the casemouth. Contained of

and incendiary composition.

Design

The 12.7×81mm cartridge allowed the Type 1 to fire at a rate of 900 RPM, but the poor suitability of the Browning's action to synchronization reduced the rate of fire to 400 RPM in synchronized installations. However, the Japanese source and Allied Intelligence reports did not mention that this machine gun had a propeller synchronization flaw.

References

Bibliography

* {{DEFAULTSORT:Ho-103 Machine Gun Aircraft guns 12.7 mm machine guns 12.7×81 mm firearms Machine guns of Japan World War II machine guns Weapons and ammunition introduced in 1941