Ho-103 machine gun
The Type 1 machine gun was a Japanese aircraft-mounted heavy machine gun widely used during World War II. It was also known as the Ho-103 in general use. The weapon itself was largely based on the American.50-caliber M2 Browning 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 than the contemporary aircraft-mounted M2 Browning machine gun by using the smaller, lower velocity semi-rimmed Breda-SAFAT 12.7 mm cartridge. The round was intermediate in length between the WWII German 13 mm calibre MG 131's ‘short’ 64 mm cartridge, and the ‘long’ 99 mm cartridge of the M2 Browning. 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 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. Types of ammunition used by the Ho-103 include:- Ball, marked with a pink or red seal around the casemouth.
- Armor piercing of Italian origin, marked with a black tip.
- Armour piercing tracer 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 of Italian origin, its body painted blue or red. Contained of PETN and incendiary composition.
- Ma 103 fuzed HEI, marked with a white seal around the casemouth. Contained of RDX and incendiary composition. Copy of the Italian fuzed HEI round with additional incendiary composition added.
- Ma 102 fuzeless HEI, marked with a dark purple seal around the casemouth. Contained of PETN + RDX and incendiary composition. Elimination of the fuze from the Ma 103 HEI round permitted additional space for explosive content. Considered an improvement over the Ma 103, detonation was achieved via crumpling of the round upon striking a target.