Two men have been found guilty of smuggling guns worth more than £100,000 into the UK and conspiracy to possess firearms with intent to endanger life.
Harry Shilling, 25, from Swanley, Kent, and Michael Defraine, 30, from Bexleyheath, southeast London, were convicted of two charges each at the Old Bailey.
The court heard how the pair were part of a gang of arms dealers who smuggled into the country a cache of automatic weapons similar to those used by the Paris terrorists.
They will be sentenced along with the three other men, David Payne, 44, from Rochester, Kent, Richard Rye, 24, from Swanley, and Christopher Owen, 30, also from Rochester, who had already pleaded guilty.
Rye and Payne also admitted a conspiracy to possess firearms with intent to endanger life.
Two other defendants, 58-year-old John Smale, and Jennifer Arthy, aged 42, both from Rochester, were cleared of the same charges.
Harry Shilling (L) and Michael Defraine smuggled deadly guns into the UK
The firearms included 22 assault rifles, like AK-47s, and nine deadly submachine guns, both capable of firing 800 rounds a minute.
The seizure, at a tiny riverside marina in Kent, was one of the biggest hauls of automatic weapons ever detected in Britain.
Video:How Gang Smuggled Guns Into UK
Investigators said the discovery highlighted poor security at small marinas around the UK coast.
During a two-month trial police provided an extraordinary level of security around the Old Bailey, details of which were kept secret from the jury in a news blackout.
Firearms officers sealed off streets and stopped traffic during the defendants' daily arrival and departure in a prison van, while others kept guard inside the building, stationed in shifts outside the courtroom door
Investigators believe the weapons were bought from the same Slovakian supplier used by Islamic extremist gunmen in the French capital last year.
The guns were thought to be destined for gangs engaged in drug and turf wars in London and the South East.
Rob Lewin, of National Crime Agency, said: "If these weapons had got out onto the open market they could have caused mass carnage.
"To put it in context, we seized four times the firepower used in the Paris attack (which killed 130 people) just before Christmas."
The NCA believes the guns were bought in a deactivated state from a company AFG which legally supplies such weapons from its base The Army Shop in Partizanske, Slovakia.
Two gang members spent time in Eastern Europe having the firearms converted back into working weapons before taking them to the French port of Boulogne, where a small boat was waiting to take them to the UK.
In text message exchanges shown to an Old Bailey jury one suspect wrote: "We now officially gangsters."
Another suspect replied: "Proper heavy and armed to the teeth."
Armed police seized the weapons during a raid on the boat moored in a marina on the River Medway at Cuxton, near Rochester.
The weapons haul was 22 VZ-58 automatic rifles, nine Skorpion submachine guns, 58 magazines, two silencers and 1,000 live rounds of ammunition.