Black Penny, the weapons used in Mexico, by the drug gangs, were largely obtained due to meekly-discriminate U.S. sales of weapons to corrupt governments/groups in central and south America, and from weapons stolen in the U.S.. Americans can commit more gun-related crimes because access to stolen guns is a breeze. In fact, it's a foolish thing to put a sticker on your window saying you're a member of the NRA, or that you are armed, because they'll rob your house when they know you're not home.
A far better utility for home defense is a dog (or many). A far better utility for personal defense is awareness and common sense training (yes, people need training in it). A gun is a lousy self-defense weapon. It is rarely accessible, at the ready, when you need it, and it can be taken away, or acquired from your household, and used against you.
As stated in earlier posts, which it seems neither you nor David bothered to read, the "right to bear arms" was included in the Constitution because of a time when armed militia could overthrow a government, when firearms were equalizers on a national scale. Nowadays governments are equipped with nuclear weapons, bacterial/chemical weapons, ICBMs, high explosives, heat-seeking missiles, tanks, etc and so on. If we were to take the context of the 2nd amendment at it's initial meaning (literal), we would allow citizens to arm themselves with nuclear weapons, bacterial/chemical weapons, ICBMs, high explosives, heat-seeking missiles, tanks, etc.
You see, it is because the world has changed, it is because the technological juggernaut of the military industrial complex has the potential to destabilize countries on a whim for profit, it is because weapons nowadays are no longer equalizers, but destabilizers, we have a problem with the literal interpretation of the 2nd amendment.
The 2nd amendment was written for a different time. Now, citizens of a nation (most any nation) can no longer hope to arm themselves if they wish to usurp control over a corrupt government. It is simply unreasonable to put assault weapons in the hands of mere citizens. It is insane to allow individuals to wield nuclear weapons. It is irrational to think that the intentions of the United States' founding fathers was to endanger the lives of its citizens by allowing them to possess mass destruction weapons. Such things did not exist at the time, were not even imagined. The best they managed at the time were cannons that blew up and flintlocks that exploded in the face of their wielders.
A balance must be made between that of allowing citizens to own weapons and protecting the citizenry from mass annihilation, and that's called gun control.