The sheeple have bleated.
“Oh, and Fruit-Loops. They all ate Fruit-Loops at some point in their lives. We must ban Fruit-Loops!”
“(... firearms designed to cause maximin human carnage in the shortest amount of time).”
That would be a 155 mm howitzer.
In WWII, some 50% of German casualties on East Front were from Artillery. Some 90% of German casualties against the Western Allies were from artillery.
And yes, possession of crew served weapons are a preexisting right documented by the Second Amendment. Rather like a ship with cannon is a crew served weapon, which was privately owned, and documented in the Congressional power to issue Letters of Marque and Reprisal.