HB 2393 amends the Texas Penal Code to criminalize the possession, manufacture, transport, repair, or sale of devices designed to modify handguns to fire automatically with a single function of the trigger. The bill adds these devices to the list of prohibited weapons, which already includes explosive weapons, machine guns, short-barrel firearms, armor-piercing ammunition, and other restricted items. However, the prohibition does not apply if the device is registered in the National Firearms Registration and Transfer Record (NFRTR) maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) or if the device is classified as a curio or relic by the U.S. Department of Justice. The bill applies only to offenses committed on or after September 1, 2025.