When fired, a bullet from one of the guns penetrated almost seven inches into a solid resin block resembling human flesh, deep enough to kill any human. The other weapon fell apart when it was fired.

Mr Schipione said: “The catastrophic failure comes about because there are no standards around the manufacture of these weapons. They are truly undetectable. They are untraceable because they have no serial numbers, no unique identifiers. They are cheap and easy to make.”