With three mostly rural, gun-friendly states right next door you would have to be pretty naive to think Mexican gangsters never sent anyone up north to pick up some guns.
While it is true that some of the guns that "go south" end up in criminal hands, those of us that live along the border know that a lot (and maybe most) arms purchased from retailers, private individuals, and at gun shows are purchased by local Mexican-Americans who are often U.S. citizens; and intended for extended family members and friends in the "Old Country." Others are obtained by professional gun runners that are only interested in money - from anybody.
Place yourself in the open warfare going on in Northern Mexico. While even the armed forces of that country cannot suppress the violence, Mexican laws for all practical purposes deny the people any means of self defense. :banghead: