Irish national Robert Keogh, 37, was stopped at 5 am on Friday 2nd August this year by Border Force officers at the Port of Dover en route from Calais.
Keogh left the UK through Dover several days earlier.
He told officers he was returning from Europe and had “just been driving around”.
However, an initial search of his car, a Volkswagen Passat, recovered a Turkish manufactured Zoraki blank firing handgun, with its barrel converted to fire live ammunition.

The gun was concealed in the car’s rear-left quarter panel.
Officers from the National Crime Agency then adopted the investigation.
Subsequent searches by Border Force officers unearthed a further 59 firearms concealed deep inside the car’s bumper and both rear quarter panels.
Keogh, from Clonee, Dublin, admitted illegally importing firearms when he appeared at Canterbury Crown Court yesterday (5th September).
He will return to court for sentencing on the 11th October.
Andrea Wilson, NCA Head of Regional Investigations, said:
“We have deprived an organised crime group of a huge haul of firearms and significantly disrupted their plans.
“These weapons would have been moved onto the criminal market and into the hands of extremely dangerous offenders.
“Although the UK’s level of gun crime is one of the lowest in the world, firearms pose massive potential for harm, making their criminal use a priority for the NCA and wider UK law enforcement.
“We work at home and abroad to prevent the flow of guns trafficked to the UK and Border Force is a vital partner in our work to protect the nation.
“This seizure is a great example of that partnership working.
Dave Hutchinson, Deputy Director Border Force South East and Europe, said:
“Keogh had made use of hidden spaces to conceal a significant number of firearms.
“The first gun was found within an hour, but it took several hours for my officers, who are all highly trained to conduct technical vehicle searches, to recover the remaining 59 weapons.
“By making this detection Border Force not only kept all of these lethal weapons off the UK’s streets, keeping people safe and protecting lives, but also took the vital first step in securing his guilty plea.
“We will continue to work with our law enforcement partners at the NCA to bring offenders like Keogh to justice and to disrupt the workings of organised criminal groups in the UK.
In England, Wales and Northern Ireland, the minimum sentence for possessing a single gun is five years in prison.
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