What is this? I keep seeing it.
I dare say, this thought that people so well read they could architect a country were not aware of the State of the Art in weaponry is rather naive.
Gatling Guns came well after the Founding, were large, heavy, hand cranked, cost between $1000 to $1500 to purchase and required a four man crew to operate. I don’t feel they can be compared to modern weapons.
The Founders were intelligent and capable men but they were not infallible. They knew that too, that’s why Amendments exist.
I can see an argument over nukes, but this "they didn't imagine assault weapons" is just some kind of gaslighting. They imagined sufficient arms to defend oneself against authority.