MI HB4479

Prohibits knowingly manufacturing, importing, purchasing, selling, or transferring firearms without valid serial numbers, as well as ghost gun precursors (unserialized frames or receivers)

Bans possession of unserialized firearms and ghost gun precursors beginning 18 months after the law takes effect, with a 90-day grace period for individuals moving into Michigan to serialize their firearms

Requires anyone manufacturing or assembling firearms without a federal license to have the firearm serialized by an authorized entity within 10 days and notify the Department of State Police director

Mandates a federal firearms manufacturing license for anyone producing firearms for profit, making more than 5 firearms per year for personal use, or using 3D printers or CNC milling machines

Prohibits all undetectable firearms (those made entirely of nonmetal substances that cannot be detected by metal detectors or X-ray machines)

First offense violations are misdemeanors punishable by up to 1 year imprisonment and/or $5,000 fine; subsequent offenses are felonies with up to 5 years imprisonment and/or $10,000 fine