Florida shooting: Why the NRA wields so much power

Every time there's a mass shooting in America there are calls for action to stop it from happening again. But any effort to introduce stricter gun laws always falters in the US Congress - and that's in large part because of the power of the National Rifle Association.

The BBC's North America Editor Jon Sopel looks at the group's influence on President Trump and other politicians.

16 February 2018