New Zealand police said they had paid about $200,000 to dozens of gun owners handing in their weapons in the first hours of the buyback event.
Nash said the Government had put aside $200 million for gun buybacks, and they would top up that figure if required.
Within weeks, members of Parliament voted to change their gun laws, banning military-style semi-automatic weapons.
"You show up, they give you a number and call you up one at a time. Once again, I can't thank the Canterbury firearms owners enough for their support and engagement in this process".
Bigger than 900 gun owners in the Canterbury position had registered at quit 1,415 firearms, he added.
New Zealand authorities hope the scheme will be as successful as one in Australia that was implemented after the Port Arthur massacre in 1996 on the island of Tasmania, where a lone gunman murdered 35 people.
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.
A new option allows owners of some prohibited firearms to have them modified by approved gunsmiths to make them lawful, with costs up to NZ$300. Provisional figures for the day saw a total of 293 prohibited firearms and 321 parts and accessories handed in.
"I didn't think this would be a fair process at all - I wasn't particularly happy about it".
Police Minister Stuart Nash said the results from the first collection were very encouraging.
"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.
All those spoken to said they were pleased with the process.
In the aftermath of the shooting, New Zealand's parliament voted 119-1 to pass a bill banning most semiautomatic weapons, as well as parts that allow lower-powered firearms to modified into higher-powered ones.At the bill's final reading, Prime Minister Jacinda Ardern, who has garnered worldwide recognition for her swift response to the shooting, gave an impassioned speech.
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.
The gun reform bill was passed by 119-1 in April to prohibit military-style semi-automatic weapons and parts that can be used to assemble prohibited firearms.
The event on Saturday is the first of 258 planned across the country until the end of the year. The suspected shooter is now facing 51 murder charges, 40 attempted murder charges and one terrorist attack charge, according to reports.