Relating to prohibiting the manufacture, assembly, or ownership of unmarked firearms and other conduct involving certain firearms and component parts of firearms; creating criminal offenses; authorizing a fee.

HB 4159 requires manufacturers and assemblers to assign and permanently affix a unique serial number to certain unmarked firearms before sale or transfer. It applies to firearms without federal/state serial numbers that don't qualify for exemptions (like pre-1968 firearms, curios/relics, or antiques). Manufacturers must apply to the state department for a serial number and affix it within 10 days of production. The department may charge a fee to cover administrative costs. This bill does not affect existing firearm owners or exempted firearm types.