From Bearing Arms:

But the thing is, it’s the right to keep and bear arms. That includes weapons like nunchucks, even if they’re essentially obsolete in most ways. That’s important because it also protects the next kind of weapon. Technology advances, after all. The Kentucky rifle was the standard civilian firearm when the Second Amendment was written, but the descriptor of “arms” protected repeating firearms when they were introduced. It means it should protect whatever firearms come next, even if we don’t live to see that day.