In the still confused aftermath of the siege, many questions have been raised about how Man Haron Monis came to be in possession of a shotgun. Prime Minister Tony Abbott – presumably better briefed than most about Monis' personal details and history – said on Wednesday that Monis had a NSW firearms licence (despite being charged with a number of serious criminal and sexual offence charges) and that gun control laws might need to be changed as a result. NSW Police swiftly rebutted the suggestion that Monis was a licensed firearm owner. Ergo, he must have acquired the gun illegally.

For someone as determined as Monis, that would not have been difficult. The number of firearms stolen and never recovered in Australia is thought to number in the tens, possibly hundreds of thousands. Moreover, significant numbers of guns are smuggled into the country illegally each year, ensuring a plentiful black-market supply for professional criminals and the criminally minded.

Police forces and gun control organisations have on occasion highlighted the growing incidence of gun-related crime (particularly in cities such as Sydney) and the need for greater controls. But resistance to such efforts is well organised and effective, not least because of the lobbying of the Sporting Shooters Association of Australia and the Shooters and Fishers Party.

It would not be doing Senator Leyonhjelm a disservice to suggest that he aspires to nothing less than the complete rollback of the national firearms agreement enacted after the Port Arthur massacre in 1996. He has repeatedly claimed that those reforms – of which a one-off compulsory buyback of automatic and semi-automatic weapons was the most prominent aspect – have not noticeably improved public safety in Australia, and that he has statistics to prove it. But lobbying for a reversion to previous state-based firearms laws is one thing – pushing for a discussion of US-style laws permitting the carrying of concealed weapons in public places, quite another. Not surprisingly, many people have questioned the basis for Senator Leyonhjelm's thinking.

Not all US states allow their citizens to carry concealed weapons, and those that do (such as Florida) do not boast noticeably safer streets or neighbourhoods than those that don't. George Zimmerman, a native of Sanford in Florida, packed a gun for "protection" of life and property, which he used to fatally shoot an unarmed teenager he "suspected" of being an immediate threat to his personal safety. Under Florida's "stand your ground" law, moreover, Zimmerman was found to have acted lawfully.

As for Senator Leyonhjelm's contention, in effect, that the Martin Place siege would not have occurred had armed citizens been present, the supporting evidence is not strong. No right-thinking person, even one trained to shoot at individuals rather than targets, would lightly challenge a dangerous and armed individual like Monis. Nor, given the likelihood of accidental shooting, would police encourage such behaviour.

That the easy availability of guns tends to increase levels of homicide, suicide and unintentional injuries and deaths, has been pretty well established, but even the likes of Senator Leyonhjelm continue to dispute it with questionable statistics. The evidence that easy access to military-style automatic weapons results in mass shootings is near irrefutable, however. Australia has had no such atrocity since 1996, though Senator Leyonhjelm continues to lament the loss of his right to own weapons designed, not for hunting or target-shooting, but for killing people.

Senator Leyonhjelm's fascination with US-style small government and rugged individualism is understandable. Nowhere is the libertarian creed espoused by the likes of John Locke and Thomas Paine taken more seriously or given greater prominence. But in its attitude to guns, the US is hardly a paragon worth emulating here.