81MM MORTAR
Cause Of A Misfire
1) Defective ignition cartridge. (2) Defective, damaged, or loose firing pin. (3) Fouled firing pin or firing pin obstructed by extraneous material. (4) Fouled bore. (5) Excess oil or water in the bore. (6) Misaligned stabilizing fin assembly. (7) Foreign matter or excess paint on round
Five Steps Of Crew Drill
Bisect Rough Level Level Elevation Level Cross-level Traverse Half The Distances To The Post And Level Cross-level
Cause Of A Cook-Off
(1) Exceeding the maximum rate of fire. (2) Smoldering debris in the barrel.
Cause Of A Hangfire
(1) Improper storage and handling of the ammunition. (2) Fouled bore. (3) Fouled ammunition
M252 81mm Mortar
M252 refers to the entire 81mm mortar system assembled.
Fire Commands
Mortar To Follow Shell And Fuze Mortar To Fire Method Of Fire Deflection Charge Time Setting Elevation
SMALL DEFLECTION/ELEVATION CHANGE
When the gunner is given a fire command from the FDC, the gunner must determine if the deflection setting is less than 60 mils, and the elevation setting less than 100 mils from the current data that is on the sight. If the new deflection is within 60 mils and the elevation is within 100 mils, it is a small deflection/elevation change
LARGE DEFLECTION/ELEVATION CHANGES
When the gunner is given a fire command from the FDC, the gunner must determine if the deflection setting is more than 60 mils, and/or the elevation setting more than 100 mils from the current data that is on the sight. If the new deflection is outside 60 mils and/or the elevation is outside 100 mils, it is a large deflection/elevation change
Gun Crew Members
Squad Leader Gunner Assistant Gunner First Ammunition Bearer Second Ammunition Bearer/Driver
CHARACTERSITICS
The M252 81mm mortar and the M224A1 60mm mortar share very similar characteristics. The 81-mm mortar is a smooth-bore, muzzle-loaded, drop fired, high-angle-of-fire weapon. The components of the mortar consist of a cannon, mount, base plate and the sight unit.
M3A1 Baseplate
The baseplate is of one-piece construction, and supports and aligns the mortar for firing
Bipod
The bipod provides front support for the barrel and carries the gears necessary to lay the mortar
Cannon M253
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.
Weights
The complete mortar system weighs 93 lbs. The cannon weighs 35 lbs, the bipod weighs 27 lbs, and the M3A1 baseplate weighs 29 lbs and the M64A1 sightunit weighs 2.25.
Elevating Mechanism
The elevating shaft is contained in the elevating leg; to the left of the elevating leg is the elevating hand wheel
Ranges
The maximum range for M889 ammunition in the conventional mode is 5,608 meters. The minimum range for M889 ammunition is 83 meters.
M177 Mount
The mount consists of elevating and traversing mechanisms and a bipod.
Rates Of Fire
The rapid rate for the 81mm mortar is 30 rounds for the first 2 minutes. The sustained rate of fire is 15 rounds per minute indefinitely.
Traversing Mechanism
The sight bracket is attached to the buffer carrier, which is fitted to the traversing screw assembly
M64A1 Sight Unit
This unit provides self-illuminating sighting capability for indirect fire in the conventional mode. deflection and elevation
