Artillery: USMC Adopt Airmobile 120mm Mortar System


July 16, 2009: After six years of development and paper shuffling, the U.S. Marine Corps have finally ordered the first twenty production model EFSS ( Expeditionary Fire Support System). Earlier this year, six systems (each consisting of two vehicles, one 120mm mortar, an ammo trailer and other gear) were issued to a marine artillery battalion for testing.

The goal with EFSS was to create a new lightweight, self-propelled artillery system. Initially, marine developers combined an existing commercial vehicle, the Supacat HMT (High Mobility Transport) with an Israeli 120 mm mortar system. The HMT is a seven ton, four wheel cross country vehicle with a capacity of 3.2 tons. It has a 180 horsepower engine and a 4x4 drive optimized for cross country work. The cab was modified to hold the five man gun crew.

There were considerable delays when it came time to figure out how to get the HMT into the MV-22 or CH-53E. The MV-22 was simply too narrow for the HMT, or most over available vehicles. The marines had to get another vehicle, the ITV (Internally Transportable Jeep.) This is a modified version of the Growler, a jeep like vehicle that usually sells for about $8,000. After all the needed mods were done with, the marines were paying about $100,000 for each ITV. The Growler is basically a modification of the old (replaced by the Hummer in the 1980s) M-151 Jeep.

The Israeli mortar system weighs 1.6 tons and is mounted on a computer controlled turntable. The mortar can fire regular 120mm shells 8.2 kilometers, or rocket assisted ones 13 kilometers. This is not as far as a 155mm howitzer can reach, but the marines feel that air power and rockets can handle longer range targets. The breech loading mortar system allows for rapid fire and the turntable system takes data directly from forward observers and quickly positions the 120mm tube to put the shells on the target. The EFSS can put shells on the target within minutes of a request. The system can fire 20 rounds in two minutes and uses a GPS assisted fire control system to provide accuracy comparable to any other artillery system.The Israeli mortar was eventually replaced with a similar French model.

The 120mm shells are also about half the weight of 155mm ones. This is to be overcome with a higher rate of fire and the use of several types of cluster bomb shells. One of these, for example, will destroy most armored vehicles, and kill or wound most troops in a 100x100 meter area. Each of the 32 bomblets can penetrate four inches of armor, but will be hitting the thinner top armor on armored vehicles. 

The marines went after the 120mm mortar, instead of another 155mm howitzer, because the mortar is lighter, faster firing, more mobile and, with the right ammunition, just as destructive as the larger howitzer.