Watch enough YouTube videos of the fighting in Syria, and you'll start to notice it: a long-tubed gun, mounted on the back of either a jeep or large, fast pickup. Usually it's blasting bunkers, blockhouses, fortified positions, or places where snipers are hiding. It even goes after tanks. And whenever it fires, the gun seems to kick up way more hell behind it than what it sends out the barrel's front end. It's the M40 106mm recoilless rifle, an American-made, Vietnam-vintage weapon that got dropped from the Army and Marine inventory back during the early 1970s. Until recently, the 106mm hadn't seen much action in the irregular wars that have swept the globe. Then M40s somehow came into the hands of rebels in Libya and Syria. Suddenly, the 106mm – light, cheap, easily transportable, simple to operate, and packing a punch all out of proportion to its modest size — has emerged as a possible Great Asymmetric Weapon of the Day.
Although the U.S. military no longer officially uses the M40, they still keep some around. A few found their way to Afghanistan where they were put to use by certain Special Forces units. The Danish and Australian armies, which acquired them from the U.S. decades ago under the Foreign Military Sales (FMS) program, used them extensively during their ground operations there.