Not only are you claiming we do not have the right to keep an imaginary weapon, there is no 7.67 Galil, but the Constitution is clear that we have the right to keep military type weapons in order for the militia to furnish their own firearms if and when called upon.
The constitution does not mention - and clearly could not - weapons which did not exist at the time the constitution was written.
I think one has to step back a little from regarding the constitution as some divine work of God, and accept that issues such as the internet and 9 mm Uzi weapons need to be viewed according the the spirit of the constitution - not according to the letter.
Galil also make a 7.62 (sorry, it was typing error before) that was used a lot in Israel during my time there.
The Constitution does not mention newspapers. It does not mention television. It does not mention lots of things that nontheless are included in its protections.
I agree these things need to be viewed in the spirit of the Constitution. And that spirit was to empower the citizens of this country, not reduce them to serfdom.