M29A1 81mm Medium Mortar
Gary's U.S. Infantry Weapons Reference Guide

TM 9-1015-200-20&P: M29A1
Complete System
Country of OriginUSA
Date Of Introduction1970
Caliber3.2 in (81 mm)
Weight121.5 lb (55.1 kg), including basic issue items
Range77 - 5,180 yd (70 - 4,737 m)
Rate of FireMaximum: 12 rounds per minute for 2 minutes.
Sustained: 3-5 rounds per minute, indefinitely
M29A1 Cannon
Weight28 lb (12.7 kg)
M23A1 Bipod Assembly
Weight40 lb (18 kg)
Traverse (approximate)95 mils (19 turns), right or left from center
Elevation (approximate)800 to 1511 mils (10 mils for each turn of elevation drum)
M3 Baseplate
Weight25.4 lb (11.5 kg)
M23A1 Baseplate
Weight48 lb (21.8 kg)
M53-Series Sightunit
Weight5.25 lb (2.4 kg)
Field of View10°
Magnification4-power, fixed-focus
Light SourceM53E1 instrument light


The M29A1 81mm mortar is a smooth-bore, muzzle-loaded, high angle-of-fire weapon. It consists of a cannon assembly, bipod assembly, and baseplate.

The M29A1 medium mortar offers a compromise between the light and heavy mortars. Its range and explosive power is greater than the M224, yet it is still light enough to be man-packed over long distances. The M29A1 weighs about 98 pounds and can be broken down into several smaller loads for easier carrying. Rounds for this mortar weigh about 15 pounds each.

The M252 replaced the M29A1 in U.S. service.

M29A1 Cannon Assembly

The cannon assembly consists of the externally threaded barrel, mount attachment ring, and base plug with a spherical projection that contains a removable firing pin for drop firing.

FM 23-90: M29A1 cannon

M23A1 Bipod Assembly

The bipod assembly consists of the elevating and traversing mechanism, and bipod legs. The bipod absorbs the shock of recoil in firing with a spring-type shock absorber.

FM 23-90: M23A1 bipod assembly TM 9-1015-200-10: cannon and bipod assembly


TM 9-1015-200-20&P: M3 baseplate
The M3 baseplate is of one-piece aluminum construction, and supports and aligns the mortar for firing. During firing, the base plug on the barrel is seated and locked to the rotatable socket in the baseplate. The barrel passes through the yoke of the mount and is secured to the shock absorber by a locking pin.

TM 9-1015-200-20&P: M23A1 baseplate
The M23A1 baseplate is of two-piece steel construction.

M53-Series Sightunit

FM 23-90: M53 sightunit
The M53-series sightunit, consists of an M128 telescope mount and an M109 elbow telescope fastened together in one unit for operation The elbow telescope provides magnification and a line of sight from which the weapon is aimed. The telescope mount secures the telescope in the correct position with respect to weapon azimuth and elevation axis.

The M109 elbow telescope is a lightweight, 4-power, fixed-focus instrument with a 10° field of view that provides the optical line of sight for aiming the weapon in azimuth and elevation planes.


The following are authorized U.S. cartridges for the M29A1 81mm mortar: The M29A1 may fire M821, M889, and M819 at reduced charges: charge 2 for training and charge 3 for combat.

The following are authorized NATO cartridges for the M29A1: Click here for more information.


FM 23-90: M29A1 squad members
The mortar squad consists of five men. Their firing positions and principal duties are as follows:
  1. The squad leader stands behind the mortar where he can command and control his squad. In addition to supervising the emplacement, laying, and firing of the mortar, he supervises all other squad activities.

  2. The gunner stands on the left side of the mortar where he can manipulate the sight, elevating gear handle, and traversing assembly wheel. He places firing data on the sight and lays the mortar for deflection and elevation. He and assistant gunner make large deflection shifts by shifting the bipod assembly.

  3. The assistant gunner stands on the right of the mortar, facing the barrel and ready to load. In addition to loading, he is responsible for swabbing the bore after every 10 rounds have been fired or after each fire mission. He assists the gunner in shifting the mortar when making large deflection changes.

  4. The first ammunition bearer stands to the right rear of the mortar. He prepares the ammunition and passes it to the assistant gunner.

  5. The second ammunition bearer is normally behind the mortar, maintaining the ammunition for firing, providing local security for the mortar position, filling sandbags, and performing other duties as the squad leader directs. He normally places out and retrieves the aiming post. The second ammunition bearer is also the squad truck driver. When his duties do not require him to be with the vehicle, he is used as an ammunition bearer (performing the same duties as the first ammunition bearer).


  1. The mortar is fired by dropping the cartridge down the cannon, base end first.
  2. The cartridge, falling under its own weight, causes the primer cap to strike the firing pin when bottom of cannon is reached.
  3. The propelling charge is ignited by the exploding ignition cartridge. Expanding gases force the cartridge from the mortar.
  4. Fins provide stability in flight for nose impact.
Double loading of mortar ammunition has resulted in catastrophic accidents. Loading a mortar weapon with two men (alternately) can be very dangerous and could prove fatal. Even with one-man loading, double loading can occur. This is especially true in rapid fire exercises. For this reason, it is imperative that there be absolute certainty that the previous round left the mortar tube before a new round is dropped in.

More M29A1 Art

TM 9-1015-200-10: M29A1 FM 23-90: M29A1
TM 9-1015-200-20&P: M29A1
M29A1 major assemblies.
Click on image to see full size: 730x470, 31K, GIF