Planning a family holiday to Tasmania, I mention that we’ll take a day trip to Port Arthur.

“What’s Port Arthur?” my daughter asks. I tell her it’s the convict site where that terrible gun massacre happened, still busy running Google searches for accommodation and car hire. Then I see she’s looking blank. Of course she is – it happened more than a decade before she was born. You’d have to be well into your 20s now to have any independent memory of that dreadful day when 35 Australians were murdered.

We haven’t had a gun massacre since John Howard and Tim Fischer had the courage to force through far tougher gun control laws and to buy back, and destroy, 660,959 guns – a great achievement of the National Firearms Agreement as well as a challenge.

It makes it easy to become complacent, to feel reassured when our guns policy is wheeled out as an example of sensible law whenever yet another mass murder highlights the lethal consequences of legal paralysis in America.

Australian gun control audit finds states failed to fully comply with 1996 agreement Read more

But the details of our firearms laws aren’t nearly as uniform, or secure, or stringent, as we might believe. They are under constant challenge from gun manufacturers devising weapons that fire far more shots, far more rapidly, than the legal categorisations ever imagined, and from a gun lobby that fervently believes those categories were too restrictive in the first place.

And it’s unclear whether political leaders still have the same resolve as Howard and Fischer did.

A review of gun laws ordered after the 2014 Lindt cafe siege in Sydney coincided with escalating warnings from gun control advocates about a new Adler shotgun that worked more like a self-loading one, even though technically it wasn’t.

It took 18 months of fraught negotiation for the federal and state governments to revise the agreement. Adler imports were supposed to be banned while governments worked things out, but Nationals senators crossed the floor to support a motion to lift the ban. The current Nationals leader, Barnaby Joyce, echoed the gun lobby’s broad argument against tighter restrictions – that guns used for crime have usually been obtained illegally so it doesn’t make sense to tighten restrictions on law-abiding gun owners.

There are many statistics to use as a counter-argument, but the most powerful is that there were 13 mass killings in Australia in the 18 years leading up to the Port Arthur massacre and there have been none since.

The new agreement did reclassify Adler-style shotguns with a capacity greater than five rounds, and maintained the main points of the 1996 agreement, but it also watered it down in other respects. And in any case it cannot be implemented without state legislation, which hasn’t happened in several jurisdictions, and in others has led to an even further weakening of parts of the law. It did include another gun amnesty, which has resulted in 30,000 weapons being surrendered.

It was a backroom compromise that no politician ever really owned or advocated or properly explained. It wasn’t even announced, just quietly posted on the attorney general’s website in February.

A review commissioned by Gun Control Australia and released this week concluded that no state was fully complying with the 1996 deal, although it said the most important parts of it were “substantially intact”.

The Shooters Union of Australia, an affiliate of the powerful US National Rifle Association, was deeply unhappy and sprang into action.

It described a meeting with the justice minister, Michael Keenan, facilitated by the Nationals senator Bridget McKenzie – one of the Nationals who crossed the floor the previous year.

Keenan, the organisation wrote on its website, reassured its representatives that the new agreement was not much different to the old one, other than the recategorisation of the Adler, that only state-based legislation could give the agreement legal effect, and that he was “on our side in what was at times a hostile environment”.

I don’t know if the latter remark is an accurate representation of the minister’s words, but the Shooters Union certainly listened to what he said about the states. It is urging its members to lobby state governments “against the unfair, unreasonable and unconstitutional vilification of firearms owners at every level of government”.

“We’ll need your help to make sure this document is not made into law in Queensland,” the Queensland chapter wrote. So far it has not been.

And it’s at state level that the gun lobby wields most power.

The Shooters, Fishers and Farmers Party in New South Wales wants to repeal the national firearms agreement altogether. It already has two members in that state’s upper house (one, Robert Borsak, famously posed next to an elephant he shot on a hunting safari in Zimbabwe). The party shocked the National party last year by taking the lower house seat of Orange with a huge swing and the benefit of ALP preferences. Next weekend, it has a real chance in another by-election in the state seat of Murray.

Australia can't be complacent about Las Vegas. Our gun laws are being eroded | Samantha Lee Read more

In Queensland, One Nation is polling 18% of the primary vote before a state election to be held by early next year. It promises to “stop making criminals out of licensed gun owners” with a 21-point plan. The very first point overturns the whole foundation of the national firearms agreement, that owning a gun is “a privilege that is conditional on the overriding need to ensure public safety”.

One Nation sees things the American way, saying Australia should “recognise that as a matter of principle, licensed firearm ownership by law-abiding citizens is a right in a free society”. Almost all the 21 points would weaken gun controls.

Gun laws are complicated and farmers and recreational shooters are the ones who feel the impact of restrictions. But their effectiveness seems obvious from the statistics.

Fischer bore much of the backlash for the Howard government’s stand. He recalled this week how his effigy was hung by a noose from a tree in the Queensland town of Gympie, where he was due to speak about the laws. And that was also a time of deep political disaffection – One Nation won 11 seats in the Queensland election in 1998.

“It was very hard work persuading people to surrender their guns. But it was absolutely the correct call,” he tells Guardian Australia.

“You have to take the argument to the public square. I took the argument to the public square, and the Australian people chose to step back from the dysfunctionality which now exists in the USA,” he said.

”It requires leadership.”

We better hope we still have it.