Wrong.  And last year they expanded it to include modern weapons.  

Caetano v. Massachusetts  (2016) : "Second Amendment “extends . . . to . . . arms . . . that were not in existence at the time of the founding.” 554 U. S., at 582.  "Second Amendment therefore protects such weapons as a class, regardless of any particular weapon’s suitability for military use."

"In Heller, we found the argument “that only those arms in existence in the 18th century are protected by the Second Amendment” not merely wrong, but “bordering on the frivolous.” 

"A State’s most basic responsibility is to keep its people safe."

"If the fundamental right of self-defense does not protect Caetano, then the safety of all Americans is left to the mercy of state authorities who may be more concerned about disarming the people than about keeping them safe."