Police said they paid more than 430,000 New Zealand dollars ($288,000) to 169 gun owners during the event. The money was paid directly into the bank accounts of gun owners.
New Zealand lawmakers in April rushed through new legislation to ban so-called military-style weapons after a lone gunman killed 51 people at two Christchurch mosques in March.
The government has set aside more than NZ$200 million to buy back weapons such as AR-15 style rifles, although many gun owners remain unhappy with the compensation on offer.
Under an amnesty, gun owners have until December to turn over their now-banned weapons.
Police said at least 14,000 guns around the country are banned under the new legislation. There are an estimated 1 million to 1.5 million guns in New Zealand and 250,000 licensed gun owners.
Under the buyback scheme, gun owners are compensated between 25% and 95% of the pre-tax price of a new gun, depending on the condition of their weapon.
People who own guns that are not banned under the new laws can also turn over their weapons during the amnesty, although they won't get any compensation. Police said a half-dozen such weapons were turned in during the Christchurch event.
Police are using hydraulic machines to crush the gun barrels and firing mechanisms of the weapons that are handed in, rendering them inoperable, before disposing of them.
Mike Johnson, an acting district police commander, said the Christchurch buyback had been a success and the attitude of gun owners "outstanding."
Police Minister Stuart Nash said the results from the first collection were very encouraging.
"Many of those who handed over firearms commented how easy the process is, how the prices are fair, and how police made the whole event go smoothly," Nash said in a statement.
But Nicole McKee, the secretary of the Council of Licensed Firearms Owners, said the government was shortchanging gun owners by trying to complete the buyback on the cheap.
She said gun owners were forced to rely on police assessments of the condition of their guns and weren't getting paid anything for the thousands of dollars they had spent on tax as well as certain accessories and ammunition.
"They do want to abide by the new laws but they have no incentive and they're having fingers pointed at them and are being treated like criminals," McKee said. "They're angry at the way they're being treated."
The council has launched a crowd-funding campaign to raise money to fight against possible further government-imposed gun restrictions.
McKee, who declined to say how much money they had raised, said they hadn't received any money from the U.S. National Rifle Association as far as she was aware.
She said the group wasn't in communication with the NRA, other than receiving a note of sympathy from the U.S. organization after the March attacks.
Hera Cook, a public health researcher who co-founded the group Gun Control NZ after the March attacks, said that before the massacre, most New Zealanders had no clue how easy it was to get hold of weapons capable of being used for mass killings.
She said she hopes the government enacts further gun control measures, including creating a register of guns and introducing shorter license periods for gun owners.
She said some of the gun owners complaints about getting short-changed or treated badly appeared to have some merit, and that "wasn't a good look" for the government.
Brenton Tarrant, a 28-year-old Australian white supremacist, has pleaded not guilty to terrorism, murder and attempted murder charges following the March attacks. He remains in jail ahead of his trial, which has been scheduled for next May.