M29, 81mm Mortar

History

In 1952, the US government replaced the standard WWII/Korea 81mm Army and Marine Corps service mortar - M1 - with a newer design M29. The "straight-tube" M29 was chosen for two reasons: longer range than their predecessors, while being lighter to maximize portability. The M29 weighs 93.5 lbs (42.411 kg), while the M1 it replaces weighs 136 lbs (61.689 kg). Army and Marine Corps mortar crews are pleased with the improvements in the new system.

The lighter design allows fire brigades to quickly get into position while carrying more mortar rounds. Mortars also provided the promised range increase, allowing fire teams to engage the enemy from a distance. The M29 would be the standard American mortar in the upcoming Vietnam War.

The 81mm platoon consists of the headquarters platoon and four mortar squads. The platoon leader is in charge - usually the lieutenant. A deputy is a deputy platoon leader, usually also a lieutenant and a platoon leader. A weapons sergeant was in charge of the ammunition and served as the primary communications officer.

Mortar Commands consist of varying numbers of personnel depending on service and battlefield conditions. During a single assault operation, the mortar barrel can engage three operators (though optimal for short periods of time) - this group of operators consists of the gunner, the gunner's assistant, and the ammunition carrier.

However, standard operating procedures recommend that most missions have five to seven staff.

The squad leader carries the sight box with the M34A2 sight and four sight posts. His position is usually behind the mortar, in a crouched position, where he can control and support the squad during fire engagements.

The sergeant also oversees tube placement, scope aiming, mortar loading and firing. The deputy squad leader is also the gunner, occupying the left side of the mortar, where he can operate the sights, wheel and gear handle for raising and lowering. His equipment alone weighs about 25 pounds.

The gunner would be ordered by the squad leader to enter the appropriate firing data into the sight and position the tube for the correct deflection and elevation for the intended target or range.

When a large deflection change is required, the gunner and gunner subs (the latter carrying ready-to-fire HE (high-explosive) cartridges and heavy 23-pound barrels) will pick up the mortar and reposition it. The gunner stood or crouched to the right of the mortar, ready to reload the gun as needed. In addition to loading, he is also responsible for wiping the barrel bore after every 10 shots or at the end of a round to ensure optimum operating conditions for the life of the mortar barrel. The 4th squad member is the 1st ammunition carrier, located in the rear right, delivering ammunition to the secondary gunner. He's sporting a 21-pound outer ring.

In a typical five-man squad scenario, the "fifth man" becomes the second ammunition carrier. As the least experienced "ammo rack" (or ammo rack), this specialist carries inner bottom plates that weigh as much as 24 pounds. Its main task is to replace the first ammunition vehicle in case the crew is injured or killed in action.

He can also provide the squad with personal security depending on the mission and maintain ammunition stocks while serving as the squad truck driver.

The mortar round is fired downward by first dropping the base end of the cartridge into the tube (this makes the M29 a "muzzle-loading" weapon). The now gravity fed mortar will drop the inserted projectile to the bottom of the tube.

At the bottom is a firing pin, which hits the bottom of the projectile with the primer cap attached. On impact with the firing pin, a small detonator was ignited, and the expanding gas propelled the mortar round from the barrel to the target along a specified trajectory.

It is not uncommon to use multiple rounds to "train" a mortar to strike a target or area.

The entire mortar system consists of three main parts: the barrel, the bottom plate and the tripod. The barrel itself consists of a tube that is externally threaded at the rear to accommodate the base plug, and has a spherical protrusion at its lower end that fits into the base's socket. The bipod legs consist of two tubular steel legs hinged on either side of the lifting mechanism.

The legs have spiked feet, and their extension is controlled by adjustable chains and springs to reduce recoil when firing. The left leg has a horizontal sliding bracket fitted with a locking sleeve and an adjustment nut on uneven ground.

This allows the rear sight at the left end of the yoke to be placed in an upright position.

Some projectiles have been provided to the M29 Fire Brigade. The M374 HE (High Explosive) round has a range of 4,934 yards. The M374A1 HE (High Explosive) can engage targets within 5,180 yards. The M375 is a general-purpose white phosphorus round with a range of 4,934 yards.

The M301A1 flare can burn the night sky for up to 75 seconds (its fall is delayed by a small parachute) and has a range of 2,296 yards. The resulting light is equivalent to the energy of 500,000 candles and will illuminate an area of ??1,200 yards.

In 1964, the US Army and Marine Corps replaced the M29 with the M29A1. The M29A1 features an improved chrome barrel that increases the rate of fire, is more resistant to battlefield wear and makes the weapon easier to clean. The M29E1 is another variant of the M29 series mortars.

The new lighter M3 baseplate is also used with the M29 for its portability needs.

Specification

Roles

Dimensions

Performance

Changes