US Ammunition Fueling Mexican Cartel Violence: An Investigation

A convoy of pickup trucks carrying men armed with heavy machine guns and .50-caliber rifles descended on the Mexican town of Villa Unión on the morning of November 30, 2019, unleashing a barrage of gunfire intended to intimidate residents and target the town hall.

The assault pinned down local and state police as the gunmen attempted to set fire to the municipal building, forcing terrified residents to seek cover. Luis Manzano, a local reporter who arrived during the shootout, described the scene, recalling the “thunder” of the .50-caliber guns and the feeling that “the ground trembled” with each shot. He had “never experienced anything like that.”

The ensuing firefight left four police officers, two civilians, and 19 cartel members dead. Investigators recovered at least 45 .50-caliber casings stamped with “L.C.” – identifying them as originating from the Lake City Army Ammunition Plant in Missouri, a U.S. Government-owned facility and the largest manufacturer of rifle rounds for the American military.

A joint investigation by the International Consortium of Investigative Journalists and The New York Times has revealed how agreements between the Army and private contractors operating Lake City have allowed .50-caliber ammunition and components manufactured at the plant to enter the civilian market and ultimately fall into the hands of Mexican cartels.

While the U.S. Domestic market for .50-caliber ammunition is relatively small, demand is high in Mexico, where cartels have the financial resources to acquire the powerful weaponry. Cartel gunmen have used .50-caliber firearms to down helicopters, assassinate government officials, and attack police and military forces.

Data shows that between 2012 and 2024, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives seized over 40,370 rounds of .50-caliber ammunition in states bordering Mexico, with approximately one-third traced back to Lake City – a larger share than any other manufacturer. The investigation also revealed that Lake City has been a source of particularly destructive ammunition, including armor-piercing incendiary rounds.

Despite declaring six Mexican cartels as foreign terrorist organizations in February 2022, the U.S. Government continues to allow the production and sale of ammunition at a plant that is supplying these same organizations. At least 16 online retailers have sold armor-piercing ammunition made at Lake City or with components from the plant.

Former ATF agent Chris Demlein emphasized the impact of .50-caliber weapons, stating, “The impact that one .50-cal has in a firefight is outrageous… They really, really tip the scale.” He explained that these weapons allow cartels to engage targets at distances exceeding a mile.

Brenda Aparicio Villegas knows the devastating power of .50-caliber weapons firsthand. Her husband, Edder Paul Negrete Trejo, was one of thirteen police officers killed in an ambush in Michoacán in October 2019. Investigators found .50-caliber casings from Lake City at the scene. She stated that her husband and his colleagues “did not stand a chance” against the cartel’s firepower.

Congress passed legislation in 2000 prohibiting the Pentagon from selling armor-piercing .50-caliber ammunition to the public, but this did not address standard cartridges. The Army allowed increased commercial activity at Lake City in the late 1990s to avoid ammunition shortfalls, including the production of 60 million .50-caliber cartridges.

Seizures of .50-caliber ammunition have increased in recent years, with the ATF seizing over 36,000 rounds and CBP seizing over 21,400 units between 2019 and 2024. Approximately one-third of the ATF seizures were traced back to Lake City.

The Army stated that its contractors are required to comply with all federal and state regulations regarding ammunition sales, and that allowing commercial sales from Lake City has saved taxpayers around $50 million annually. Olin Winchester, the current operator of Lake City, did not respond to requests for comment.