More than 700 firearms have been confiscated as part of a five-year campaign to prevent readily convertible replica guns from entering the UK.
Police made 74 arrests leading to 50 convictions and searched 133 premises.
The plan was spearheaded by the National Crime Agency and worked in partnership with the Guardia Civil in Spain, British police, border police and international arms dealers.
In total, 703 firearms have been recovered since Project Vizardlike started in 2019
It targeted what are known as forward-facing blank-firing weapons, which are similar to weapons like Glocks and can be converted into lethal weapons.
Roy Godding, head of the NCA National Firearms Targeting Centre, said: “Our analysis showed a trend of serious and organized criminals wanting this weapon.”
The NCA has been working with border police to identify packages containing firearms from abroad.
A man has been sentenced to 11 years in prison after 26 firearms were found in his home.
Seven cases involved a potential terrorist threat.
Charles Yates, deputy director of the NCA, said: “There is no doubt that very significant damage was prevented.”