The details of the buyback scheme are yet to be determined, but the regulatory framework is outlined in a supplementary order paper that will be added to the Arms (Prohibited Firearms, Magazines and Parts) Amendment bill.
The bill, which bans military-style semi-automatics (MSSAs), assault rifles and their associated components with some exemptions, will pass its remaining legislative stages in the House today with the support of all parties except for Act.
It will receive its Royal Assent tomorrow and be in force on Friday.
The National Party will attempt to amend the bill today to extend exemptions for competitor shooters, and for police to use Firearms Prohibition Orders to go after gang-owned illegal firearms, but these are unlikely to have parliamentary support.
The bill does not include an exemption for competitive shooting, but Nash has said it could be considered in the next round of gun law reforms.
National Party police spokesman Chris Bishop said that just created uncertainty.
"Competitive shooters are placed in quite an invidious position. They're going to have to essentially give up their guns, and it may be that in six or nine months when phase two of reforms goes through, they may be exempted in which case they go out and buy their guns again.
"That's why we think it needs to be sorted out now."
The regulations for the buyback scheme are expected to be considered by Cabinet in May. The amnesty for surrendering firearms is in place until the end of September, but can be extended.
The Government has estimated that the buyback scheme will cost up to $200 million, but gun lobby groups have said it could be up to $1 billion if it included loss of income, including compensation for the 500-odd gun dealerships that may not be reimbursed by overseas suppliers.
The regulations do not specifically mention gun dealerships, but allow for compensation to dealers for banned firearms and gun parts to be included.
But they also specify that the scheme can exclude "any economic loss", "any consequential loss", "any loss for business interruption", or "any loss attributable to intrinsic or sentimental value".
They include provision for a maximum limit in "specified circumstances", such as setting a maximum number of prohibited magazines that a person can be compensated for.
Nash said independent advisers will develop a compensation price list for Cabinet approval, while a separate expert panel of advisers will look at compensation for high-value firearms.
"The regulations will create a framework to set compensation based on make, model and condition of the items. They will provide for rights of review and appeal," Nash said.
They also allow the Commissioner of Police to determine the amount of compensation, including how to calculate compensation.
Surrendered firearms will become the property of the Crown. What happens then is still being determined, but they may be sold to police or the Defence Force, where appropriate, or destroyed.
Nash said transitional measures are also being put in place, including for businesses that make or export firearms or gun parts about to be banned.
"This includes weapons which were in transit from overseas when the ban took effect. Customs officials may deliver them to police as part of the amnesty and buyback arrangement.
"I can reassure firearms owners there will be plenty of time for them to hand over their weapons as part of the amnesty and to have their compensation processed under the buyback as well."
Act leader David Seymour said by restricting compensation, the Government was discouraging people from handing in their firearms.
"If a significant number of weapons aren't handed in, we risk creating a large black market of dangerous weapons without any regulatory oversight.
"That may be a more dangerous world than we had prior to March 15."
The passage of the bill today will conclude the first phase of the Government's gun law reform, which has seen emotional pleas to Parliament in support of the law from the Muslim community, broad support from hunters and farmers who sought wider exemptions to the ban, and vociferous opposition from gun lobby groups that claimed the ban was too harsh on law-abiding firearms owners.
A second phase, scheduled for later this year, will look at issues such as the licensing regime and a national firearms register.
