Relating to: prohibition against undetectable firearms, possessing a frame or receiver of a firearm without a serial number, and providing a penalty.

AB 321 prohibits the possession, sale, or manufacture of undetectable firearms - those not detectable by standard metal detectors or security scanners - and requires serial numbers on firearm frames or receivers. It directly affects individuals who own or handle such firearms or unmarked firearm components, with specific exemptions for law enforcement, military personnel, and pre-1968 firearms. Violations carry penalties of Class G felony (possession of undetectable firearms), Class H felony (possession of manufacturing plans), or Class I felony (unmarked frames/receivers). The law aims to enhance public safety by making firearms more detectable during security screenings.