Media playback is unsupported on your device Media captionA guide to the weapons available in the US and the rate at which they fire Six days after the Christchurch mosque attack, New Zealand Prime Minister Jacinda Ardern announced a ban on "military-style" semi-automatic rifles, prompting questions in the US. Following a series of mass shootings in the US in recent years, there has been little in the way of sweeping gun-control reforms.On the federal level, at least, the interest and attention in new legislation has led to almost no action in decades, despite numerous polls showing widespread public support for measures like strengthened background checks and banning certain types of high-capacity gun magazines and military-style assault rifles.The Trump administration has issued a regulatory ban on bump-stock modifications that allow semi-automatic weapons to fire like machine guns, and there have been some tweaks to the background check database for gun-store purchases. Last March, Donald Trump entertained the notion of more ambitious, "comprehensive" legislation, telling senators pro-gun lobbyists had little power over him. But no such talk from the president since.Here are five big obstacles that stand in the way of the kind of the US taking the kind of quick, major changes to firearm policy being advanced in New Zealand.The NRA Image copyright Getty Images Image caption A woman shows off a model gun and holster at an NRA fashion show The National Rifle Association is one of the most influential interest groups in US politics - not just because of the money it spends on lobbying politicians, but also because of the engagement of its five million members.It opposes most proposals to strengthen firearm regulations and is behind efforts at both the federal and state levels to roll back many existing restrictions on gun ownership. In 2016 the NRA spent[1]

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