The intent of the 2nd Amendment was to keep the newly formed Congress from taking away the states' rights to have a militia - not to make sure that Frank the wack-a-doo can more efficiently shoot up a campus or office building or that Bubba can turn a duck or deer into confetti.
Actually, the intent was to keep check on the federal government. Especially at the time, and although less effective still true, a ruling power is kept in check by an armed populace, and the founders knew that. The "Don't worry about protecting yourself, we'll protect you" doesn't really address who protects us from the aforementioned "we", and it falsely assumes "we" has my best interest in mind (on my typical soapbox we wouldn't have had this debate if someone had bloodied Jefferson's nose w/r/t unenumerated powers).
Beyond the Constitutional issues, what makes the gun control lobby so convinced that controlling an inexpensive yet highly demanded product works? Prohibition? The War on Drugs?