A former Army recruiter from San Antonio has admitted he funneled dozens of assault rifles to operatives of Mexico’s Gulf Cartel last year by organizing other soldiers to help him buy the weapons. During the investigation, agents used another confidential informant to buy firearms from Prezas in August 2015 and watched Prezas as he loaded five of them into his government vehicle at his recruiting station in San Antonio and drove to Pharr in the Rio Grande Valley. In all the transactions, Prezas supplied Zamudio, Salazar and Brown with the money to purchase the firearms and paid them a cut for their efforts, making the trio “straw buyers,” the Prezas plea deal said. The move was applauded by gun violence prevention groups that advocate for closing the so-called “private sale” loophole, which allows gun owners in most states to legally sell their guns without a background check. […] sales have continued on private groups on Facebook and the ATF notes the proliferation of social media networks has been a challenge in the fight to control illegal gun distribution. A handful of cases have been scattered around the country, such as two members of California’s National Guard assigned to the armory in El Cajon, California, who were charged last year with selling ammunition and high-grade weapons to someone they believed was working for a Mexican drug cartel.