The M129 is an automatic grenade launcher developed as an aircraft-mounted weapon in service with the United States military.
History[]
Developed in the 1960s, the M129 is a redesign and improvement of the earlier M75 to correct a major design flaw, in which excessive torque was created due to the barrel being positioned below the cam drum.
Over 1,667 launchers were manufactured, initially by Philco-Ford before 1971, and then by the Maremont Corporation from 1972 onwards.
Between 1967 and 1968, the M5 subsystem of the UH-1 Iroquois was modified to accommodate the M129. It had also replaced the M75 in the development of the M8 subsystem during the Light Observation Helicopter competition. The M129 is also selected as an optional weapon for the M28 turret subsystem in the AH-1 family, as well as being part of the XM51 of the AH-56A Cheyenne, and in the XM94 of the UH-1H.
Design Details[]
The M129, like the M75, is an air-cooled, electrically-powered, cam-driven automatic grenade launcher. Instead of the cam drum being above the barrel, it is concentric to the barrel, eliminating the M75's torque problems. The 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.
The weapon also features improved mounting. The cyclic rate was also increased to 400-440 rounds per minute. Ammunition is fed into the weapon via a belt, but it also comes with an innovative improvement; a special feed tray that allows the weapon to fire both low-velocity (40×46mm) and high-velocity (40×53mm) grenades.
The weapon also features a mechanism that provides instant interchange between electric operation and a manual hand-cranked operation.
It also boasts a dynamic braking system which ensures that the barrel always stopped in the forward (safe) position when the firing trigger is released. This meant that the weapon is stopped only after a full revolution of the cam, with the barrel forward and no live round could be potentially chambered.
Variants[]
- XM173 - The XM129 modified with the hand-cranking system in lieu of the power drive system. It was not adopted.
- XM182 - A modified version of the XM129 developed in 1968 with spade grips for mounting on ground-based vehicles, such as the M706 Commando Armored Car. It was never adopted.
Gallery[]
