In a statement, the Public Security Police said that the defendants were given effective prison sentences of eight, six and five years.
Another defendant involved in the case was sentenced to three years and nine months for possession of a prohibited weapon.
According to PSP, the group's leader created and led an organisation to sell firearms in Portugal, which he modified from over-the-counter weapons, and ammunition, which he manufactured.
The PSP explains that the 'modus operandi' of this criminal organisation consisted of ordering and acquiring hundreds of weapons from a gunsmith in Slovakia and the Czech Republic and, later, transporting them to Portugal, where the organisation had a workshop prepared for the transformation of the weapons into firearms, as well as the manufacture of ammunition.
During the investigation, the PSP Department of Weapons and Explosives resorted to different national and international information sharing mechanisms related to the illicit sale and possession of firearms in Portugal and Europe, the statement added.
The PSP adds that the investigation lasted 22 months and that seven people were arrested, 47 search and seizure warrants were carried out, 13 of which at home and 34 outside of the home, and 176 weapons and more than a thousand rounds of ammunition were seized.