>"the Second Amendment predates machine guns"

That statement is false. Repeating firearms like the Puckle gun predate the bill of rights by ~75 years.

More importantly, the Founders were hardly unfamiliar with privately owned military firepower. The Constitution expressly authorized Congress to grant letters of marque, and the government commissioned privateers to attack enemy shipping using their cannon-armed privately-owned warships.

If you want to change an amendment do it the correct way, repeal it.