AK-47 assault rifles used by terrorists Charlie Hebdo attack most popular illegal weapon in Europe.

There is no definitive count, but the bloc estimates that around half a million lost or stolen firearms remained unaccounted for within the EU. And that only accounts for weapons that were once registered and later went missing. Many of the automatic “war weapons” are illegally trafficked from the Balkan Peninsula and former Soviet Bloc states, where millions of leftover arms from the Croatian, Bosnian and Kosovo wars are regularly stolen, bought and transferred in small numbers, mostly to organized crime clients in Southern Europe, according to Gunpolicy.org. In France, there are an estimated 10 million to 20 million illegal weapons alone, according to a Christian Science Monitor report.

Guns can be acquired in the EU through a number of means. A .44-caliber Desert Eagle is advertised for 1,250 euros, or $1,481, by an anonymous European arms dealer on the Deep Web. The dealer ships that weapon through the mail. With the proper connections, which the Charlie Hebdo gunmen appeared to have, an AK-47 costs around $400 to $900 in certain European markets, and about $1,100 to 1,800 in France, according to a Bloomberg report.

In Kosovo, less than 20 years out of the Balkan’s most recent all-out war, gunrunning is rampant. A 2007 report quoted a young Kosovar gunrunner who said an AK-47 made in China can be picked up in his town for just 250 euros, and for only 50 euros in neighboring Albania, which along with two neighboring Balkan states, is on its way to becoming an EU member country. The gunrunner said many of the guns that run through Kosovo come from Serbia and Macedonia. Many, like the gas pistols converted to lethal handguns, are brought to Albania and smuggled into Western Europe, he said.