Agree with what you say, but better be careful with the term "assault rifle", as the people on the other side of this issue will (correctly) point out that the military definition of an assault rifle includes that it has a fully automatic mode - and such weapons are effectively already banned in the USA. Also, another good one (that that you didn't mention), the weapon name prefix "AR" does not stand for "Assault Rifle".

What to say instead? Perhaps that semi-automatic weapons, and magazines over a certain size, should be banned.