CA AB1263

Prohibits knowingly or willfully causing, aiding, abetting, or facilitating the unlawful manufacture of firearms, including assault weapons, .50 BMG rifles, machineguns, and firearms made using 3D printers or CNC milling machines; violations are a misdemeanor

Expands the definition of "digital firearm manufacturing code" to include computer-aided manufacturing files and codes for producing large-capacity magazines, machinegun components (switches/auto-sears), silencers, and firearm accessories

Creates a rebuttable presumption of liability for owners or managers of websites that distribute digital firearm manufacturing code and encourage users to manufacture firearms

Requires firearm industry members selling unattached barrels, firearm accessories, or firearm manufacturing machines to provide purchasers with notice that unlicensed manufacturing is generally illegal, obtain acknowledgment of the notice, and verify the buyer is at least 18 years old

Imposes a 10-year firearm possession ban on individuals convicted on or after January 1, 2026, of specified misdemeanors including manufacturing undetectable firearms, using 3D printers/CNC machines to make firearms unlawfully, or aiding unlawful firearm manufacture