More than 830 firearms and thousands of rounds of ammunition have been seized by anti-terror police and officers from the National Crime Agency (NCA) during four weeks of raids.
Investigators heralded the results of the crackdown as a "significant" success in the battle to prevent terrorists – and other criminals – from obtaining potentially lethal weapons and carrying out a Paris-style attack in the UK.
The haul included; 11 assault rifles, with a fully-loaded AK47; two machine guns; one Skorpion submachine gun; about 200 handguns, including Zoraki, Tanfoglio GT32 and Makarov pistols; 99 rifles; 153 shotguns; 200 antique firearms; and 4,385 rounds of ammunition.
Police said some of the weapons were seized from registered firearms dealers who had their licenses revoked, while others are thought to have been smuggled into the UK from the continent.
About 100 knives, 80kgs of illegal drugs and more than £500,000 (€ 580,000, $620,00) in cash were also confiscated by officers.
In total, some 282 people have been arrested in connection with the raids.
Investigators said the joint operation between the NCA and the National Counter Terrorism Policing (NCTP) unit had enhanced their understanding of the illegal firearms market.
The swoops also saw officers credit intelligence received from the public during Crimestoppers' #GunsOffOurStreets campaign, which has been running since October.
Detective Superintendent Nick Wilcox, of NCTP, said: "Counter-terrorism officers continue to plan and prepare in light of world events such as the attacks in Paris – but we want to remain on the front-foot and stop terrorists obtaining guns in the first place.
"Low firearms availability is a major advantage in the UK. In many other western countries someone like Muhiddin Mire, the man who attacked innocent passers-by in Leytonstone tube station last year with a knife, could probably have got hold of a firearm and one serious injury could have become tens of deaths.
"Communities defeat terrorism – our collective safety depends on everyone's efforts and we need your help to prevent a marauding firearms attack."
The Met Police this week launched a seven-day gun amnesty in a bid to remove even more weapons from UK's streets, following last year's offer of cash rewards of up to £2,000 to informants who told them where illegal weapons were located.
Chris McKeogh, deputy director of the NCA, said: "The surge of activity across the whole of the UK has yielded significant results – from the seizure of illegally held firearms and ammunition, to the number of reports we received from members of the public via Crimestoppers.
"Collectively, we will build on what we achieved in this short period of time to ensure that we develop the best intelligence we can about the firearms cross-over between organised crime and terrorism.
"Gaining the confidence of the public to come forward with information about illegal firearms is key to any campaign and I would like to thank all those who had the courage to speak up. As a direct result of your call or report, we are able to protect the public and reduce the risk posed by those with access to illegal firearms.
"This is not over though. One gun in the wrong hands is too many, so please think hard and if you know something, pick up the phone anonymously."
Anyone who has any information about illegally held guns or ammunition can either contact the police or, if you wish to remain anonymous, call Crimestoppers on 0800 555 111.