The police confiscated live ammunition from a passenger travelling at Christchurch Airport this afternoon.
A spokesperson said a firearm was initially legally checked in by its owner and made inoperable to take on a domestic flight.
They say at around 12:30pm, a possible round was spotted during security screening.
The airport police checked the luggage, and found that two rounds had been inadvertently left in a magazine, but not in the firearm itself.
The officers seized the rounds and the owner of the firearm was reminded about the requirements around transporting guns.
No furthern action will be taken.