Under the new law - which is being rushed through Parliament under urgency - that type of gun would be made illegal.
Cabinet agreed to overhaul New Zealand's gun laws when it met on Monday – "72 hours after the horrific terrorism act in Christchurch."
On Thursday, Ardern announced a ban on all military-style semi-automatics (MSSA) and assault rifles in New Zealand, as well as a ban on related parts used to convert these guns into MSSAs, along with all high-capacity magazines.
Davis' weapon would have been made illegal, as it was a semi-automatic firearm capable of being used with a detachable magazine which holds more than five cartridges.
"I handed it in because it was the right thing to do," he said.
"The safety of New Zealanders is greater than my need to own a gun of this sort."
It is likely there would be other MPs doing the same as Davis and handing their guns over to police.
A spokesman for the Minister of Defence Ron Mark would only say the minister would "absolutely comply with the law".
National's Rodney MP Mark Mitchell – a former policeman and former head of a military contracting business in the Middle East – said he didn't have any guns to hand over to police.
Neither did Labour MP Kieran McAnulty, who is based in the Wairarapa.
Police Minister Stuart Nash said he had no guns to hand over to police either.
National's Northland MP Matt King said he has two guns – a shotgun and a .22 bolt action rifle – but won't be handing them over to police as they are for farming purposes and would not be illegal under the new law.
The day after Ardern announced the ban, more than 1000 people have notified police to say they wish to hand in their firearms.
The total number of firearms in New Zealand is estimated to be 1.2-1.5 million – there are 245,000 firearms licences in the country.
The Government has put in place a gun buyback scheme, expected to cost between $100 million and $200 million.
As of 3pm on Thursday, an Order in Council – signed by the Governor General – established changes to classifications in the Arms Act to mean some firearms have been reclassified as military style semi-automatic firearms (MSSAs) and are illegal.
This was done to prevent stockpiling of weapons.
The Order in Council is a transitional measure until the wider ban takes effect after the legislation has passed.
An amnesty was put in place, allowing people who have these weapons to hand them over to police.
