The regurgitated yarn ends with the computer being "destroyed" by Customs.
It has sparked earnest and vigorous debate on gaming websites and on social media machine, Reddit.
Customs say they investigated the story when it first surfaced on social media last week.
They can find no record of the incident at any of their ports.
However, a spokeswoman confirmed that the importer has laid a complaint with Customs over the alleged damage to the machine.
"Customs has no record of inspecting the parcel and the complainant is unable to provide shipping details for us to follow-up," she said.
"Based on the details we have been given by the complainant it is likely that the computer has been inspected en route to New Zealand rather than at the border here due to the fact that the method of resealing this particular package, as advised by the importer, is not one that NZ Customs uses."
She doubted Customs offers would "destroy" a computer in such an incident.
The owner, when contacted, refused to comment while Customs were investigating his complaint.
His machine is currently being fixed by a Wellington computer store.
The G1 Assassin 2 motherboard, complete with signature "Locked and Loaded" heat pipe pistol or machinegun design, is readily available for sale in New Zealand, and on global retail giant, Amazon for US$732.59.
The Reddit thread where it was first posted last week has prompted more than 650 comments.
Many blame Customs for destroying the machine.
"They don't need to destroy anything to see that it isn't a real gun," one user said.
Another said: "Please tell me you were compensated or were at the very least given an apology!"
But others took the side of the airport workers.
"They are just doing their job," one post said.
"Maybe don't bring something that clearly looks like a gun to an airport next time. What did you think would happen?"