Three men and a woman have gone on trial accused of illegally importing 31 automatic weapons into the UK.
The Old Bailey heard the gang used a boat to smuggle the weapons, worth more than £100,000, across the Channel.
The jury heard defendant Harry Shilling, 25, from Swanley, Kent, came up with the plan and paid for the guns.
Prosecutors said the weapons would have been sold into the criminal underworld and were capable of “unleashing carnage on a terrifying scale”.
The three other defendants are Jennifer Arthy, 42, and John Smale, 58, and Michael Defraine, 30. All four are on trial for gun smuggling and possessing firearms with intent to endanger life.
Mr Shilling, Mr Defraine, from Bexleyheath in Greater London, Mr Smale, from Rochester in Kent, and Ms Arthy, who lived on a houseboat in Cuxton, Kent, deny the charges against them.
Ms Arthy’s partner and skipper of the boat David Payne, 43, has already pleaded guilty to the illegal importation of firearms along with two other men.
Prosecutor Duncan Atkinson QC said the smuggling plan was not disputed as Mr Payne, Richard Rye, 24, and Christopher Owen, 30, had already pleaded guilty. He told jurors that it was for them to decide who else was in on the plot.
The guns – 22 assault rifles similar to AK-47s, and nine Skorpion sub-machine guns – were brought into the UK from Boulogne in France on a 38ft (12m) cruiser, the MV Albernina, the jury heard.
All had originally been deactivated but were reactivated before they, along with a large amount of ammunition, were smuggled up the Medway into Kent, arriving near Cuxton Marina on 10 August last year.
But the National Crime Agency (NCA) had the plotters under surveillance and swooped to seize the cache before it could be buried and then passed into the wrong hands, the court heard.
The prosecution alleges Mr Shilling came up with the plan and paid for the guns, with help from Mr Defraine and “loyal lieutenant” Rye, who acted as a “go-between” with others.
Payne brought the guns into the country on board the Albernina, which was paid for by Rye and Mr Shilling, the court heard.
Ms Arthy, along with Mr Smale and Mr Owen, both from Rochester, were allegedly recruited to help buy and prepare the vessel and unload its cargo.
On arriving back in the UK, Payne texted Rye to say “All done”.
An hour later, the prosecution says Mr Shilling sent Mr Defraine an encrypted email saying “There (sic)home”, and then a few minutes later, another email saying “We now officially gangsters”.
Mr Shilling also exchanged messages with a mystery contact, called “B”, to arrange delivery of the guns, the court heard.
The court heard each of the 22 Czech-manufactured assault riles would have fetched up to £4,000 even though they were sold at “shockingly low” prices in Eastern Europe.
The Skorpion machine guns, which were originally developed for use by Czech special forces, would have netted £3,500 apiece.
Mr Atkinson said: “The prosecution contends that these guns were more than trophies – they were working weapons and they came with a large amount of working ammunition.”
The trial, which is expected to last a month, continues.