The "gun control" lobby's goal is to remove all guns from society - a noble one, and one that I would support if it wasn't a utopic vision of how it could be. In the real world, some people are psychotic and are able to access guns - and most of the time, it's in a way that's already illegal. The CT shooting, for example, the perp stole the firearms and killed the owner with them before going on a spree.
I take a different tact - tinfoil hat on - the 2nd is about keeping the government in check. We are slowly having our rights eroded by more legislation and a more powerful government. Citizens are surveilled without warrant, jailed without charge, property seized without cause - all in the guise of "anti-terrorism". Local police forces all have SWAT teams (comprised mainly of the same "peace" officers) with automatic weapons. The National Guard is deployed in warzones to supplement the volunteer military. I've seen the argument of "what good is your gun against all that" - and that's the point.
I believe, whether or not it's the goal, that all this can be used to subdue the general populace and enslave them. And that's what the 2nd is supposed to fight against. According to many polls, apparently I'm not in the majority (but that's sketchy to believe based on the blatant control of the media machine) - but I believe as a lawful citizen of a sane state of mind I should be able to access the same weaponry as my peace police force. I face the same dangers they do, after all, and the Supreme Court upheld that the police have no duty to protect. Try suing them for a crime committed against you next time it happens, if you don't believe me.
It doesn't mean we should give automatic weapons to citizens either - we could go the other way and remove the ability of law enforcement to have automatic weapons.