The plastic 3D-printed replica pistols formed part of the display stands Mr Patel presented to at least three senior New Zealand security officials in July.
Mr Patel, the most senior Trump administration official to visit the country so far, was in Wellington to open the FBI's first standalone office in New Zealand.
Pistols are tightly restricted weapons under New Zealand law and possessing one requires an additional permit beyond a regular gun license.
It was not clear what permissions Mr Patel had sought to bring the weapons into the country.
Inoperable weapons are treated as though they are operable in New Zealand if modifications could make them workable again.
The officials sought advice on the gifts the next day from the regulator that enforces New Zealand's gun laws, Mr Chambers said.
The guns Mr Patel gifted to the law enforcement chiefs were not semi-automatic models, now prohibited after the Christchurch massacre. »