SpursFanFromAround already explained that Fast and Furious was already exposed and proven. It was funded by our government. That is a fact. But, regardless of Fast and Furious, criminals in Mexico were well-equipped before it. The disproportionate nature of guns owned by criminals and guns owned by ordinary citizens is off the charts, and it has been for a very long time. My wife is in her mid 40s and she tells me how these people ran towns by fear back when she was a teen. It was so much so, they (criminals) would impose curfews to citizens with the threat of murder if they were walking about after dark. So, if you were in some sort of work that require you to work after dark, you would have to arrange it with them, or take your chances of being murdered. That is no joke. And, because the level of corruption in all levels of government, you could not go to police for fear that they would tell on you or kill you themselves.
All that said, the 2nd amendment to the constitution wasn't for citizens to protect themselves from "criminals." It was for citizens to have means to protect themselves against tyranny. The idea was to establish balance of power between the government and the people. That balance of power did not exist in the monarchy they (our forefathers) fought against for independence. Now, limiting gun ownership simply because some crazy individual got a hold of a gun and killed people is stupid. It solves nothing. The problem that needs solving is figuring out how that deranged individual got a hold on the gun and address that. For example, in the case of Sandy Hook, charges needed to filed against the mother for negligence. But, even deeper than that, we need to figure out why are we breeding "violent crazies." If you take a gun away from a crazy person set to kill people, they will do it with a knife, a bar, with their bare hands, you name it. To me, it is dumb to focus in "mass" killings. After all, would you be less upset or distraught if a loved one is killed by a deranged individual if your loved one was the ONLY victim? I don't think so. The fact that your loved one was one of many will not be any worse than if he or she was a solitary victim.