A 20-year-old San Antonio man is headed to federal prison for 40 months after firing a stolen 9mm handgun that had been fitted with a machine-gun conversion device near Joint Base San Antonio-Lackland, federal prosecutors said. Joseph Anthony Jimenez admitted firing the weapon into a field outside the base on Aug. 17, 2024, later telling authorities he accidentally shot a friend before tossing the device. He pleaded guilty in December and has been in custody since his arrest last year.
Prosecutors' account
According to the U.S. Attorney's Office, Western District of Texas, court records show Jimenez fired the stolen 9mm twice on Aug. 17, 2024, while it was equipped with a machine-gun conversion device. Prosecutors say he then ditched the modified handgun by throwing it over an apartment complex perimeter fence. He was arrested on a state warrant on Aug. 29, 2024, federally indicted on Nov. 6, 2024, and transferred to federal custody on Nov. 21 before entering a guilty plea on Dec. 3, 2025. Assistant U.S. Attorney Sarah Wannarka handled the case.
How a 'Glock switch' works
The ATF explains that a machine-gun conversion device, often nicknamed a "Glock switch," turns a semi-automatic pistol into a weapon capable of fully automatic fire and is treated as a machinegun under federal law. Federal agents say these devices can transform otherwise lawful handguns into fully automatic firearms, sharply increasing the risk to anyone nearby.
How investigators connected the incidents
Investigators matched shell casings found near Lackland with casings recovered at a child's birthday-party shooting later that same night and eventually located the modified Glock in a storage unit, as reported by MySA. Local deputies say video and other evidence tied Jimenez and others to a stolen vehicle used in the shootings. According to authorities, one witness at the party was injured when Jimenez allegedly fired the weapon. Officers say the ballistic match between the two scenes helped secure search warrants that led to his arrest.
Sentence, prosecution and agencies
A federal judge handed down the 40-month sentence after Jimenez pleaded guilty to possession of a machinegun and possession of an unregistered firearm, the U.S. Attorney's Office said. The investigation pulled in multiple agencies, including the ATF, FBI, the Air Force Office of Special Investigations, the U.S. Air Force 502nd Security Forces Group, the San Antonio Police Department, the Bexar County Sheriff's Office and the Texas Department of Public Safety. Assistant U.S. Attorney Sarah Wannarka prosecuted the case for the government.
Legal implications
Federal law treats machine-gun conversion devices as machineguns under the National Firearms Act, and convictions for possessing an unregistered machinegun can carry prison terms of up to 10 years, the ATF and prior federal releases note. Prosecutors say the devices create a particularly serious public-safety threat because they allow rapid, automatic fire from common handguns.
The U.S. Attorney's Office shared news of the sentence on X via U.S. Attorney WDTX, and officials say the case is part of ongoing efforts to get illegal conversion devices off the streets near military installations and residential neighborhoods. The punishment follows a string of other federal prosecutions focused on Glock switches and similar add-ons.
