Officers swooped on the Polish gunrunner as he was transporting weapon parts from Austria.
A search of his home and nearby forests revealed dozens of illegal firearms.
The stash, buried underground in barrels, included pistols, rifles, revolvers and automatic weapons such as Škorpion machine pistols, as well as over 80 essential weapon parts and more than 20,000 pieces of ammunition, Europol said.
The man was a former licensed gun dealer, which gave him specialist knowledge of European laws, including a loophole he exploited to run his illicit business.
He imported firearms kits from Austria, which he then assembled in Poland before selling them abroad.
"Further investigation proved that the suspect had indeed sold dozens of illegal weapons, including automatic guns and pistols, to criminal networks operating in Germany and Poland,” the EU’s law-enforcement coordination agency said in a statement.
“This led to the suspect being designated a high-value target by the authorities.”
Swedish authorities found that weapons provided by the suspect had been used there by a criminal gang for contract killings.
The Europol investigation involved law enforcement from five EU countries—Austria, the Czech Republic, Germany, Poland and Sweden. Europol also sent two weapons experts to Poland to help in the technical assessment of the weapons haul.
