Thirty-one countries – including the United Kingdom – have taken part in pan-European raids to take down gun traffickers.
Operation Conversus searched 143 houses.
They made 22 arrests and seized 129 firearms.
Law enforcement teams also confiscated 1,492 weapons ready for conversion and 24,735 rounds of various ammunition.
Also in the hoard were six hand grenades, 276 kilos of dynamite, 299 detonators, and more than 21 kilos of gun powder.
Romania and Bulgaria authorities led the operation.
A spokesperson for Europol said:
“As the procurement of illegal firearms has become increasingly difficult and expensive, individuals and organised crime often resort to converted alarm and signal weapons.
“These blank-firing pistols have become a weapon of choice for criminals, as certain models have proved to be easily converted to discharge live ammunition.
This conversion process involves changing the weapons to make them capable of firing live ammunition, which is illegal.
“Once converted, the weapons are distributed through illicit channels, contributing to the proliferation of illegal firearms.”
