Whenever a conversation on gun restrictions and the Second Amendment come up, Joe Biden always defaults to the position that the Second Amendment doesn't mean that you can have any weapons that you want.
During a speech Biden said, “And I might add: The Second Amendment, from the day it was passed, limited the type of people who could own a gun and what type of weapon you could own. You couldn’t buy a cannon.”
He's actually wrong though. What would be the purpose of bringing a knife to a gunfight?
Obviously, the Second Amendment isn't quite that extreme, but what I've tried to do is reduce it down to the most complex form to explain the flaw in their thinking.
Democrats like Biden think that our government should be able to have any type of weaponry they want, but we the people should be limited to making sure that we don't have such strong weapons.
From the Washington Post,
The meaning of the Second Amendment — “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed” — has long been debated. But experts said Biden especially mischaracterized it.
“Everything in that statement is wrong,” said David Kopel, the research director and Second Amendment project director at the Independence Institute. After 1791, “there were no federal laws about the type of gun you could own, and no states limited the kind of gun you could own.” Not until the early 1800s were there any efforts to pass restrictions on carrying concealed weapons, he said.
“I think what he’s saying here is that the Second Amendment was never understood to guarantee everyone the right to own all types of weapons, which I believe is true,” said Kermit Roosevelt, a constitutional law professor at the University of Pennsylvania. “As phrased, it sounds like the Second Amendment itself limited ownership, which is not true.”
Having a well regulated militia and rights to bear arms that shall not be infringed means just that. If you restrict what we can have, that is an infringement. Don't like it? Find another country with weaker laws.