The Associated Press published an article that talks about gun trafficking going south from the US into Mexico. It states that some of these guns are AK-47s, "military-style" weapons (which, by-the-way, to liberals includes most hunting rifles too), and Barrett 50-caliber rifles.
Isn't it interesting that the US government has sold the Mexican government (both military and police) Barrett 50-caliber rifles, M-16s and AR-15s for years. Also, take note that the author admits that the hand grenades, rocket launchers, etc have been coming from Central America. I'll take a leap and say that they AK-47s are coming from Central America too. Remember, the Soviets funneled weapons into Central and South America through Cuba for years. Those weapons are just lying around now waiting to be sold to the highest bidder--or the bidder that is most likely to kill you if you don't sell them what they want.
Simply put, the US government sells the Mexican government American-made weapons. We find American-made weapons in Mexico and say ma-and-pa's guns are being trafficked south.
We need to quite kissing the rear-end of the Mexican government and apologizing for the elephant in the room that they put there. Mexican corruption is the reason for drug cartels being stocked better than the Mexican military--not us! We did them a favor by giving them the needed weapons to fight crime and they've shot themselves in the foot.