September 22, 2009: The U.S. Army has successfully tested a new, inexpensive, guided mortar shell. The RCGM (Roll-Controlled Guided Mortar) works by using a special fuze that includes a GPS unit and little wings that move to put the 120mm mortar shell closer to the target than it otherwise would be. Thus all you need to convert existing 120mm mortar shells to RCGM is the RCGM fuzes (which handle the usual fuze functions, as in setting off the explosives in the shell, as well as the guidance functions.)

Now that the army knows RCGM works, the manufacturer (General Dynamics) has to refine it for greatest accuracy and reliability, and a price the army can justify. All troops would do to use RCGM, would be to put each fuse into device that would transfer the target GPS coordinates, then fire the shell. It would also be possible to program each fuze once it is screwed into the shell, via a metal probe that would go into a hole in the fuze, transfer the data, and signal that that the transfer was accurately made.

In any event, guided 120mm shells just got a lot cheaper and easier to use. This is particularly crucial for 120mm mortars, which are used by units close to the front lines, where not a lot of ammo can be carried, and resupply is riskier since the enemy is so close. Thus a guided 120mm shell means fewer shells getting fired to get the job done. And RCGM is not the first attempt to produce a guided 120mm mortar round. There are several, and there another American guided mortar shell project already being tested.

Two years ago, the U.S. sent laser guided 120mm mortar rounds to Iraq and Afghanistan for testing. The XM395 Precision Guided Mortar Munition had been in development for twelve years, and was almost cancelled at least once because of the delays. The 38 pound XM395 round has a range of 7.5 kilometers, and will land within three feet of where the laser is pointed. Unguided mortar shells cannot put the first round that close, and requires firing several rounds, and adjusting aim, before you get one on the target. A guided mortar round is very useful in urban warfare, where a miss will often kill civilians. The 120mm mortar round has about five pounds of explosives, compared to 15 pounds in a 155mm shell. The smaller explosive charges limits collateral damage to civilians. The XM395 began arriving in Iraq and Afghanistan last year, but wide distribution of the XM395 is not expected until next year. Each round costs about $40,000, much more than RCGM is expected to cost.

Every U.S. infantry battalion is equipped with 120mm mortars.