Neither side in an argument can find the truth when both make an absolute claim on it.
Rifle? Why not.
Automatic rifle? Fine by me, virtually no crimes have ever been committed with automatic weapons. (someone explain to the media what automatic really is, please!)
Grenade launcher? Errr, getting sketchy.
Patriot missile battery? Ummm
Not too many people would argue that nuclear weapons should be legal for private ownership. Similarly, not too many people would argue that you should never be able to own a gun at any time or place. While I hate the cliche, the answer is surely somewhere in between.
One of you will end up here next!
All that is irrelevant.
Citing the "fire in a crowded theater" condition on the First Amendment is not applicable. What the gun grabbers are trying with their false analogy is to say that all people should have their mouths banned, because they may be used to yell "fire" inappropriately.
The damage is done by yelling "fire", not by having a voice. The prohibition against yelling "fire" is a prohibition against certain vocal acts. Laws already exist that prohibit certain actions with guns, ie, armed robbery is a felony, hence the application of the "Fire in a Crowded Theater" constraint on the First Amendment is already in place as a constraint on the Second Amendment.