San Antonio Man Sentenced to Federal Prison After Firing Machine Gun Near Air Force Base

SAN ANTONIO - The San Antonio man who prompted a military response by firing a weapon outside Lackland Air Force Base in 2024 was sentenced today to 40 months in federal prison for possession of a machine gun and unregistered firearm, announced U.S. Attorney for the Western District of Texas, Justin R. Simmons.

According to court documents, Joseph Anthony Jimenez, 20, fired a stolen 9mm pistol equipped with a machinegun conversion device (MCD) into a field near Lackland Air Force Base on two separate occasions on Aug. 17, 2024. Also known as a "Glock switch," an MCD allows a firearm to fire as a fully automatic weapon. An MCD is defined as a machinegun under the National Firearms Act, even when not installed. Jimenez admitted to accidently shooting his friend later that same day, then throwing the MCD-equipped handgun over the perimeter fence of an apartment complex.

Jimenez was arrested on a state warrant on Aug. 29, 2024. He was federally indicted with possession of a machine gun and possession of an unregistered firearm on Nov. 6, 2024, and transferred to federal custody on Nov. 21, 2024. On Dec. 3, 2025, Jimenez pleaded guilty to both charges.

"Beyond the basics of responsible gun ownership, everyone must understand the dangers of machinegun conversion devices," said U.S. Attorney Simmons. "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. Thanks to the response from the JBSA Defenders, along with the subsequent investigation by local and federal authorities, Jimenez is being held accountable for his poor decisions and violations of federal law."

"The illegal possession and use of a machinegun conversion device represents a serious threat to public safety," said Bureau of Alcohol, Tobacco, Firearms and Explosives Special Agent in Charge Michael Weddel. "These devices turn otherwise lawful firearms into fully automatic weapons, dramatically increasing the potential for mass harm. ATF remains committed to working alongside our federal, state, and local partners to identify, investigate, and hold accountable those who endanger our communities through the use of illegal firearms and conversion devices."

The ATF, FBI, Air Force Office of Special Investigations, U.S. Air Force 502nd Security Forces Group, San Antonio Police Department, Bexar County Sheriff's Office, and Texas Department of Public Safety investigated the case.

Assistant U.S. Attorney Sarah Wannarka prosecuted the case.

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