M75 40mm Grenade Launcher
The M75 grenade launcher is a 40x53mm, cam-operated, electric motor driven, air-cooled, grenade launcher that has a rate of fire of 215-230 rounds per minute. The large drum cam feeds linked ammunition into the weapon and also controls the rate of fire. The weapon's barrel cycles back and forth as part of the firing process, with the rear battery position effectively locking the cartridge in during the fire phase of the operation cycle.
In 1961, Philo-Ford filed the first patents for an automatic grenade launcher using the US Army's new high velocity 40mm ammunition. This new weapon, the first of its kind in the US Army, was subsequently designated as the XM75. The weapon was subsequently type classified as the M75. The weapon was quickly added to the arsenal of weapons being used in experiments with armed helicopters. Philco-Ford was tasked with developing an armament subsystem utilizing the weapon for the US Army's new UH-1A helicopter. The resulting XM138, involving an turret fitted to the nose, was quickly integrated into the proposed organization for armed helicopter units. Tests were also conducted with the weapon mounted on a tripod for ground use.
A redesign of the XM138 led to the XM5 armament subsystem by 1964. This system was essentially identical to the XM138, but featured a revised ammunition feed. The nose turret system, later type classified as the M5, was intended for the UH-1 series of helicopters, but was also used on the ACH-47A helicopter. The M75 was also utilized in the early prototypes of the XM8 armament subsystem and in the prototype XM9 armament subsystem. A gun pod for fixed wing aircraft, designated the XM13, was also developed.
The weapon design reflected its fast development cycle. A 1964 report on Army aircraft armament deemed the weapon inherently unsafe in its basic design, which allowed for live rounds to be left in the breech after firing had ceased. The weapon's mechanism allowed for it to "run away" under certain circumstances as well, functioning without any user input. Development of an improved derivative, the XM129, had begun in 1963 to rectify the problems. Further development of the M75 ceased in 1967 as the XM129 reached maturity. This weapon, type classified as the M129, subsequently replaced the M75 in subsequent applications requiring a weapon of this type. A total of 494 M75s had been built.
|Join the GlobalSecurity.org mailing list|