Recently, Blake Franko of the National Interest published an article about the ubiquity of the Kalashnikov AK-47 and its variants. He focused on how its popularity is the result of its reliability in the hands of all kinds of shooters, in the toughest and dirtiest environments. This reliability made the AK-47 a formidable adversary and a valuable acquisition for American troops in Vietnam, when their M16s were jamming from shooting and local conditions.

But there is more to the story that is worth exploring. It might have been useful to go on for a few lines to explain why the AK-47 was so reliable in those conditions. The Kalashnikov’s success has to do with its gas operating system.

Like the M16 and many other rifle arms since the early 1900s (and a few pistols, most notably Israel’s Desert Eagle), the AK-47 is gas operated. That means that the recycling of the action after a round is fired is not the product of the blowback of the fired round, as in most pistols and a few submachine guns like the old Thompson, but by the pressure of the hot, highly pressurized gas in the barrel of the newly expended round. Through a little port in the barrel, this highly pressurized gas can push back to operate the action and reload another round for fire, whether automatic or semiautomatic.

But there is a big difference between the Kalashnikovs and the M16 types. The former use a plunger-type action, essentially a rod whose front end captures the pressure of the round ignition, pushing the rod back to recycle the action. This is called a long-stroke gas piston. The latter use a hollow tube to return the gas pressure to the action to be recycled, which is called direct gas impingement. The AK-47 is more reliable in dirty conditions than the M16 variants, while the latter is more accurate in combat situations. Here’s why: the AK-47 design protects the action from contaminating powder debris. That way, it doesn’t foul up so quickly—but it has a long metal rod bobbing back and forth that interferes with accurate shooting. The gas action design of the M16s doesn’t have that long rod bouncing in the way, so it is more accurate in automatic or rapid-fire semiautomatic action. But it brings the polluted gas back to the action, and therefore fouls more easily than the AK-47. We’ve dealt with this problem for decades now, and we are still struggling with it.

There is a relevant cultural and historical legacy at work here. American arms are informed by a history and a legacy in which a colonial farmer could shoot down a squirrel or a British officer with a rifled musket from a hundred yards. Russian arms, meanwhile, are informed by a history of a lot of peasant soldiers slogging through the mud to engage. No wonder, then, that the two have evolved such distinct comparative advantages.

Fritz W. Ermarth is a retired government official with a long biography in intelligence and national security affairs. Over his academic and professional years, his main focus has been the USSR and Russia. He is also an energetic shooter and reloader.

Image: U.S. Navy SEAL brandishing an AK-47. Wikimedia Commons/SEAL + SWCC