A new study has found that the number of firearm injuries in the US decreases dramatically during National Rifle Association conventions, casting doubt on the claim that most gun injuries are caused by inexperienced users.

Researchers from Harvard Medical School and Columbia University reviewed 10 years of data on emergency department visits and hospitalizations during the NRA’s convention dates, as well as the three weeks before and three weeks after. They found that firearm injuries decreased by an average of 20 per cent during NRA conventions.

The reduction was most pronounced among men, and in states with some of the highest rates of gun ownership, the researchers wrote in a letter to the New England Journal of Medicine.

The finding contradicts many gun advocates’ argument that firearm injuries are caused by poorly trained users. While the study could not prove cause and effect, the researchers say it is notable that firearms injuries decrease so much during the NRA conventions, where some 80,000 experienced gun owners are kept busy.

“The fact that you observe large relative reductions in firearm use during this brief period [is likely] because they’re either at the convention, or because venues where they might use firearms are more likely to be closed during the convention,” Anupam Jena, one of the study’s authors, told TIME.

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Her colleague, Andrew Olenski, added: “I would liken this to driving. Even if you’re an experienced driver, you’re always at risk of getting in an accident and having an injury.”

Yet many pro-gun groups have long advocated that firearm injuries can be avoided with the right kind of training. A recent post on the pro-gun blog The Truth about Guns argued that a single, two-day course would "often get even the greenest of noobs shooting somewhere on par with some police officers”.

The NRA even hosts a firearm safety training course for children, called the Eddie Eagle Gunsafe programme, which it claims can help prevent firearm accidents among those in pre-kindergarten through fourth grade.

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Even President Donald Trump appeared to embrace the idea while advocating for his proposal to arm teachers in the wake of the school shooting in Parkland, Florida.

While some argued that arming teachers would make schools less safe by increasing the risk of accidental shootings, Mr Trump assured supporters that 10 to 20 per cent of the American teaching population are “very gun-adept people”.

“These teachers love their students,” Mr Trump told the crowd at the Conservative Political Action Conference. “And these teachers are talented with weaponry and with guns. And that’s – they feel safe.”

The researchers seemed to disagree.