San Antonio Man Sentenced to Federal Prison for Illegal Machinegun Use Near Laughlin AFB

Joseph Anthony Jimenez, 20, of San Antonio received 40 months in federal prison on April 8 after he fired a stolen pistol outfitted with an illegal machinegun conversion device outside a military installation, triggering a military response and drawing in a multi-agency federal investigation that stretched from the moment he pulled the trigger to a guilty plea more than a year later.

Court documents show Jimenez fired a stolen 9mm pistol fitted with a machinegun conversion device, commonly called a Glock switch, into a field near Joint Base San Antonio-Lackland on two separate occasions on August 17, 2024. The small attachment converts a semi-automatic handgun into a fully automatic weapon capable of firing continuously with a single trigger pull. Under the National Firearms Act, the device is legally classified as a machinegun even when not attached to a firearm, making simple possession a federal crime punishable by up to 10 years in prison.

The day's events compounded quickly. Later on August 17, Jimenez accidentally shot a friend, then disposed of the modified handgun by throwing it over the perimeter fence of a nearby apartment complex. He was arrested on a state warrant 12 days later, on August 29, federally indicted on November 6, 2024, and transferred to federal custody on November 21 before entering a guilty plea on December 3, 2025.

U.S. Attorney Justin R. Simmons, whose office prosecuted the case in the Western District of Texas, did not minimize the stakes. "Beyond the basics of responsible gun ownership, everyone must understand the dangers of machinegun conversion devices," Simmons said. "This individual set an example of what not to do, and he should feel fortunate that the consequences of his actions were not far worse, even deadly."

The Bureau of Alcohol, Tobacco, Firearms and Explosives, the FBI, and the Air Force Office of Special Investigations jointly investigated the case. The ATF has pursued machinegun switch enforcement across the full Western District of Texas: a 2024 federal complaint out of Del Rio charged a San Antonio man with possessing two handguns each equipped with a switch, reflecting the same crackdown that now extends to communities surrounding Laughlin Air Force Base.

Jimenez pleaded guilty to possession of a machinegun and possession of an unregistered firearm. Federal law treats the Glock switch as an unregistered machinegun under the National Firearms Act regardless of whether it was manufactured as a firearm, a detail that significantly lowered the legal threshold prosecutors needed to meet.