IZHEVSK, Russia — The nickname of this town, home of the factory that makes Kalashnikov rifles, is the “Armory of Russia.” Over the years, it has armed a good number of other countries, too, as the lathes and presses of the Izhevsk Machine Works clanged around the clock to forge AK-47s and similar guns for insurgents and armies around the world.

But these days, many of Izhevsk’s weapons are headed somewhere else: the United States.

Despite the gun’s violent history — or perhaps because of it — American hunters and gun enthusiasts are snapping up tens of thousands of Kalashnikov rifles and shotguns. Demand is so brisk that the factory has shifted its focus from military to civilian manufacture over the last two years. United States sales of the civilian versions, sold under the brand name Saiga, rose by 50 percent last year, according to officials at the factory, known as Izhmash.

Over all, the United States is the world’s biggest market for civilian guns. That is partly because of comparatively lenient gun ownership laws, which have become a topic of renewed debate after a rampage last month in which a masked gunman killed 12 people and wounded 58 in an Aurora, Colo., movie theater. Although no Kalashnikovs were involved, police say one weapon used by the man charged with the shootings, James Eagen Holmes, was a popular semiautomatic pistol made by the Austrian company Glock.

Russian weapons accounted for a tiny portion of the $4.3 billion American gun market last year, but Saiga sales rose far faster than the overall growth rate of 14 percent in 2011.