M252 81mm Medium Mortar
Gary's U.S. Infantry Weapons Reference Guide

FM 23-90: M252
Complete System
Country of OriginUK (L16)
Date Of Introduction1987
Caliber3.2 in (81 mm)
Weight121 lb (55 kg) (including basic issue items)
Range91 - 6,133 yd (83 - 5,608 m)
Rate of FireMaximum: 30 rounds per minute for 2 minutes.
Sustained: 15 rounds per minute, indefinitely
Unit Replacement Cost$24,717
M253 Cannon
Weight35 lb (16 kg), with blast attenuator device
M170 Mount
Weight27 lb (12 kg)
Traverse (approximate)100 mils (10 turns) right or left from center
Elevation (approximate)800 to 1515 mils (10 mils for each turn of elevation drum)
M3A1 Baseplate
Weight29 lb (13 kg)
M64-Series Sightunit
Weight2.5 lb (1.1 kg)
Length4.375 in (111 mm)
Width4.75 in (121 mm)
Height7.375 in (187 mm)
Field of View17° (302 mils)
Magnification1.5 unity power
Light SourceSelf-contained, radioactive tritium gas (H3)


The M252 81mm mortar is a smooth-bore, muzzle-loaded, high-angle-of-fire weapon. The components of the mortar consist of a cannon, mount, and baseplate.

The M252 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 M252 weighs about 93 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.

M253 Cannon Assembly

The cannon assembly consists of the barrel that is sealed at the lower end with a removable breech plug, which houses a removable firing pin. At the muzzle end is a cone-shaped blast attenuator device (BAD) that is fitted to reduce noise. The BAD is removed only by qualified maintenance personnel.

FM 23-90: M253 cannon

M177 Mount

The M177 mount consists of elevating and traversing mechanisms and a bipod.

FM 23-90: M177 mount, folded

M3A1 Baseplate

FM 23-90: M3A1 baseplate
The M3A1 baseplate is of one-piece construction, and supports and aligns the mortar for firing. During firing, the breech plug on the barrel is sealed and locked to the rotatable socket in the baseplate.

M64-Series Sightunit

FM 23-90: M64 sightunit
The sightunit is the device on which the gunner sets deflection and elevation to hit targets by using the elevation level vial and the cross-level vial. After the sight has been set for deflection and elevation, the mortar is elevated or depressed until the elevation bubble on the sight is level. The mortar is then traversed until a proper sight picture is seen (using the aiming posts as the aiming point) and cross-level bubble is level. The mortar is laid for deflection and elevation when all bubbles are level. After the ammunition has been prepared, it is ready to be fired.

The two major components are the elbow telescope and sight mount. The elbow telescope has an illuminated cross line. The sight mount has a dovetail, locking knobs, control knobs, scales, cranks, and locking latch.


The following are authorized (Standard B) cartridges for the M252 81mm mortar: Click here for more information.


FM 23-90:  M252 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 to the left side of the mortar where he can manipulate the sight, elevating handwheel, and traversing handwheel. He places firing data on the sight and lays the mortar for deflection and elevation. He makes large deflection shifts by shifting the bipod assembly and keeps the bubbles level during firing.

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

  4. The first ammunition bearer stands to the right rear of the mortar. He has the duty of preparing the ammunition and passing it to the assistant gunner. He is also the squad driver.

  5. The second ammunition bearer stands to the right rear of the mortar behind the ammunition bearer. He maintains the ammunition for firing and provides local security for the mortar position. He performs other duties as the squad leader directs.

More M252 Art

FM 23-90: M252 FM 23-90: M252

M252 Photos - Click on image sample to see full size image.

Army website: M252
10th Mountain Division's 1st Battalion, 87th Infantry Regiment
Orgun-E, Afghanistan
U.S. Army Photo by SPC Timothy J. Belt
1024x880, 260K, JPEG
Marine Corps website: M252
81mm mortar platoon, Battalion Landing Team 1st Bn., 2nd Marines, 22nd MEU
Forward Operating Base Hit, Al Anbar province, Iraq
Marine Corps Photo by Sgt. Richard D. Stephens
1024x1300, 250K, JPEG