Yeah, there's the argument about, "well if they take those, the next step is all guns." When were full auto guns restricted? The 30's? Al Capone and friends maybe? What if they put AR's into a similar category? It's not impossible to get a full auto, you just have to want it enough. How about giving everyone grenades/grenade launchers? Rockets? Artillery? Tanks? Fighter/bombers? Where do you draw the line? I know I don't want to have grenades running around everywhere like pistols are nowadays. You hunting deer with that grenade? Or maybe you're fishing.... "No I'm keeping it to lob at the cops who come to take my guns." (Please note sarcasm.) I fully recognize that the 2nd Amendment is not about hunting, but about keeping arms in the hands of the citizens, but where is the line?
Putting all the constitutional stuff aside, just as a matter of basic morality, I don't think anyone has the right to initiate force (and let's face it, government is nothing but organized force) against anyone as long as the other person is not threatening anyone else's equal rights. People ought to be able to do whatever they want as long as they don't hurt other people. The mere possession of a weapon, by itself, is not a threat to anyone's rights. If you use it in a certain way, or if you are mentally unstable enough, it could rise to that level, and then other people would be justified in using force/government to stop the threat.
Gun control schemes are overbroad remedies. They restrict the rights of the 300-some million people in this country who didn't violate anyone's rights with a gun yesterday, just to TRY to keep a few madmen from getting a hold of something that they are likely to be able to find anyway if they want it bad enough.
This kind of legislation is called a "prior restraint," and in the context of First Amendment law, has been declared unconsitutional. "Prior restraint" means that anyone who wants to exercise a certain right has to jump through some hoop. Prior restraints are unconstitutional as applied to speech because they are overbroad... impacting everyone with legitimate speech just to catch the few perpetrators of "bad speech" out there... and also because the government should have very limited power to say what is "bad speech" in the first place, since the main political function of the right to free speech is to be able to keep the government under control.
Prior restraints should not be tolerated on the right to bear arms either, and for the exact same reasons. Politically, the 2A serves the same purpose as the 1A, and all the other amendments in the BOR... to keep the government from getting too powerful. I don't know why you are sarcastic about being armed to prevent the police from violating your rights... that is precisely the main reason for the people to be armed.
Ultimately, it is all about preventing this:
http://www.hawaii.edu/powerkills/20TH.HTM