Numerous groups, from Public Citizen to Move To Amend, are working hard on this last effort to say that "Corporations are not people and aren't entitled to the rights of personhood," and "Money is not the same thing as speech." If successful, such a constitutional amendment would overturn the "new laws" promulgated (unconstitutionally) by the court in 1886 (corporate personhood) and 1976 (money = "free speech").
The NRA and their weapons-manufacturing buddies aren't the only bad actors trying to damage our democratic republic through what were once illegal methods to corrupt public officials. Companies from the fossil fuel industry to the GMO industry to Silicon Valley have been doing it for years.
They're all symptoms of the real and larger problem: that the Supreme Court has ruled that corporations and billionaires can own a virtually unlimited number of state and federal politicians. These newly empowered billionaires are now even bragging about that ownership, as you can see with the recent Koch brothers announcement that they're injecting an eye-popping $400 million into the election this fall.
Only when we get money out of politics, like the good citizens of Montana did back in 1912, will we be able to deal with the NRA and their ilk on anything like a level playing field.