Steve Bain shoots semi-automatic rifles for sport, and personally owns an armoury spanning modern military weapons to an original World War II rifle.

Aiming down the damp, grassy rift that is the Kaitoke Rifle Range in the backblocks of Upper Hutt, Steve Bain bangs out an ear-piercing wallop of a shot, then four more in quick succession.

The kickback is familiar to Bain, who takes all of a few seconds to load, cock and raise a loosely-held AR15 semi-automatic rifle to his eye.

A rush of power comes from firing a weapon associated with mass shootings, but for Bain, secretary of the Wellington Service Rifle Association, firing such a gun is sport.

And for the nearly 250,000 New Zealanders armed with at least a standard firearms licence, it's available in a rapid-fire package for less than $1500 at your local firearm retailer.

CAMERON BURNELL/STUFF Can you spot the difference? This rifle, being fired by Wellington Service Rifle Association secretary Steve Bain, can be owned on a standard firearms licence without registration. See the below photo for a comparison.

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In New Zealand's love affair with firearms, the relationship with semi-automatic tools of war is increasingly fraught.

The law that defines semi-automatics – written after the 1990 Aramoana massacre – is now considered patchy by police, poorly written by the gun lobby, and such a "bloody mess" when applied, a dispute over gun imports will now be settled by the courts.

There's more of these rifles out there than we know. Of the estimated 1.5 million firearms owned in New Zealand, 15,000 are registered military-style semi-automatic rifles (MSSAs).

But these are only the registered semi-automatics, which fit the legal definition of an MSSA: a gun with a free-standing pistol grip, magazine of more than seven bullets, or muzzle flash suppressor.

To buy and use such a rifle requires an E-Category endorsement of a standard firearm licence, prerequisites being a reference from a shooting club or another bona-fide reason requiring one (often for pest-control or for gun collections).

But there's a loophole in the law, according to police, that has an unknown number of these guns in the hands of regular licence holders.

CAMERON BURNELL/STUFF This rifle, for comparison with the above photo, is deemed a military-style semi-automatic which is registered to a special firearms licence. But there's little difference between this model, and one that can be bought on a standard licence.

Case in point: today at Kaitoke, we're looking through the military-grade scope of the Wellington Service Rifle Association's AR15, suitable for standard licence holders.

It's in an A-Category configuration, meaning it doesn't fit the MSSA definition due to a strip of moulded-plastic connecting the handle-grip to the shoulder-butt of the gun, and a magazine which only holds seven bullets.

Insert the 30-round magazine from Bain's personal AR15 – an E-Category model with a free-standing handle – and the club gun is now an MSSA.

"The only real difference in them is the stock, and it doesn't have a muzzle flash ... but apart from that, you could stick a 30-round magazine in that and go for your life," Bain says.

Bain meets other service rifle shooters monthly for competitive shoots like the Kaitoke Turnaround, which begins with a row of 10 shooters stood facing away from the range.

At the blow of a whistle, all 10 spin around and drop onto mats covering chip gravel and rusted bullet casings. Rifles in hand, they unleash 20 rounds in what remains of 20 seconds, competing to get the best score on targets 100 yards - 90 metres - away.

CAMERON BURNELL/STUFF The ownership of semi-automatic rifles is a contentious issue for the firearm community and police, with a dispute over imports reaching the courts.

The shooting club is a community that helps regulate its own, Bain says. He receives two emails a month from newcomers looking to shoot semi-automatics and, if they're considered reasonable people after a couple of shoots, a reference for endorsement is provided.

"You can pretty much tell straight away if they're a loose unit.

"We administer the rules quite effectively. The criminals don't, and that's never going to bloody stop."

But police aren't confident in the ability to regulate the weapons, and can't enforce a licensing regime that is breached by simply swapping out a magazine.

Police declined multiple requests for an interview but its view is apparent in a briefing on firearms provided to Police Minister Stuart Nash in September.

Signed off by Acting Deputy Commissioner Richard Chambers, it says the risk to public safety "sadly played out" in the killing of Natanya and Wendy Campbell by Quinn Patterson at his home near Whangarei in July 2017.

"Some of these statutory gaps were exploited by Quinn Patterson who illegally acquired an 'A Category' semi-automatic through using a friend's firearms licence, and later converted it to a MSSA by adding a high capacity magazine.

"Purchase of high-capacity magazines is unregulated and does not require a firearms licence."

And it's not an isolated case.

CAMERON BURNELL/STUFF Secretary of the Wellington Service Rifle Association Steve Bain says the community of specially licensed shooters self-regulates and ensures bad characters aren't able to own the weapons.

This week, Tribesmen gang member Rawden Yates is standing trial in Whangārei District Court, accused of killing fellow gang member Kimble Moore with an AK47.

And Rollie Heke, who hammered police officers with semi-automatic gunfire on a Morrinsville street in August 2017, later admitted - and is awaiting sentence - using a firearm against law enforcement.

A growing number of firearms stolen each year - 807 in 2017 compared to 505 in 2008 - poses a risk of further criminal harm, police say.

The importation of parts built for MSSAs, but imported as A-Category parts, poses another risk.

"Some in the firearms community will see closing off the identified loopholes as an erosion of the privilege they have earned by being considered fit and proper to possess a firearm," Chambers said.

But despite police concerns Nash does not see a need to tighten the law, or restrict any licence owner to acquire a semi-automatic.

"Even if you have an [standard] licence ... you've still got to go through a reasonably involved process, you've still got to character check, police have still got to visit your home, you've got to get references from friends.

"What I would loath to do is make serious changes through regulations ... if you're going to make changes to the way you police the Arms Act, then it should be done through legislation."

Any proposed changes were unlikely to be considered soon, he says.

CAMERON BURNELL/STUFF Secretary of the Wellington Service Rifle Association Steve Bain shoots semi-automatic rifles for sport, and personally owns an armoury spanning modern military weapons to an original World War Two rifle.

New Zealand Police Association president Chris Cahill says this isn't good enough.

"The Minister is too cognisant of a small group of gun lobbyists, of which the influence on him is out of proportion to the actual views of firearm owners."

Cahill says there's a clash between the police view, the ministerial view, the "vocal and aggressive" gun lobbyists, and the need to enforce an outdated Arms Act.

"MSSAs are not needed, these things are designed to kill people. I don't know of any Olympic event where they shoot AR15s.

"A strong discussion needs to be had over the needs for MSSAs to be available in New Zealand, and if so, who actually needs them."

CAMERON BURNELL/STUFF Wellington's service rifle shooters monthly for competitive shoots such as the 20-20, which begins with a row of ten shooters stood facing away from the range.

Nash has long heard complaints from the firearm community that the law was being inconsistently applied - such as with differences in gun safe requirements demanded by regional arms officers.

And he has heard police on the issue of imports.

"Police are placing very strict conditions upon who can import these and the terms and conditions under which they can be imported."

He's asked police to take a look at "innovative solutions" in this area. For instance, (and Nash reiterates he's yet to receive advice or make a decision) imports could be allowed, but on the condition an E-Cat endorsed licence be produced at the point of sale.

ROSS GIBLIN/STUFF Police Minister Stuart Nash says there will be no changes to the Arms Act without the public having a say though the legislative process.

Recently some retailers have had previously-accepted import permits for claimed A-Category configuration AR15s and parts declined, with police arguing they are born of MSSAs.

Police, which in May took the import application process from the hands of regional arms officers to a centralised office in Wellington, say it's simply a more consistent application of the law.

Gun City owner David Tipple said it's more than an incorrect interpretation of the distinction between rifles and MSSAs made in the Arms Act.

He's filed an appeal against the police decision to refuse those applications. .

KEVIN STENT/STUFF Police Association president Chris Cahill says access to semi-automatics under the current law is a "pandora's box".

Council of Licenced Firearm Owners (COLFO) chairman Paul Clark agrees the law is poorly written, causing a "bloody messy" situation.

The perceived risk of semi-automatics is out of proportion, he says, when the vast majority of gun owners act within the law.

Clark acknowledges there have been deaths, but points to criminal intent and mental health as the fundamental issues.

"It doesn't require a semi-automatic weapon, whether it's got a high-capacity magazine or otherwise, to shoot a lot of people."

Describing police policy, he uses a word fondly held in the firearm community: "ultra-vires", meaning beyond legal authority.

Like Gun City, COLFO is considering legal action to defend the semi-automatic status quo.

"If the police end up throwing the baby out with the bathwater, you're going to drive guns into the black market.

"If you think you've got a problem now, you haven't seen anything."