Yeah it’s completely untrue. There were lots of very powerful weapons available in those days that rival today’s assault weaponry (even from medieval times) and the 2nd amendment makes no mention of that.

The 2nd amendment is a principle, not a law. It’s a universal, in time and space, foundation upon which we base our laws. The Founders were well aware of this and it actually was their intention.

These were highly educated enlightenment thinkers, to assume they didn’t foresee weapon innovation is just silly.