Rep. Thomas Massie, R-Ky., who leads the House Second Amendment Caucus, introduced legislation this week that would lower the minimum age for buying a handgun to 18.

Under current federal law, the minimum age for buying a handgun from a licensed dealer is 21, and the minimum age for buying a rifle is 18.

In the wake of the Florida school shooting, many politicians and President Trump have supported the idea of raising the minimum age for rifles to 21. The teen shooter in Florida used an AR-15 style rifle to kill 17 people.

But Massie's bill goes in the other direction, and would instead create a single, 18-year-old minimum age for both handguns and rifles. Massie and other gun proponents have argued that the best way to prevent mass shootings is to use their rights under the Second Amendment to defend themselves.

After Trump tweeted out support for raising the minimum age for rifles to 21, Massie tweeted back to ask why younger people shouldn't be allowed to defend themselves.

Why should a 20yr old single mom be denied the right to defend herself and her kids? We should lower the age to buy a handgun to 18, instead of raising the age to buy an AR15. SAD! https://t.co/riLrfXZlbb — Thomas Massie (@RepThomasMassie) February 22, 2018



Massie has also introduced legislation that would let teachers arm themselves. He and Trump agree on that idea — Trump has said that as many as 10 to 20 percent of teachers in any given school might agree to be trained and carry concealed weapons in order to stop future attacks.