Criminals and violent extremists continue to seek ways to acquire firearms through the production of privately made firearms (PMFs). PMFs can be easily made using readily available instructions and commonly available tools, require no background check or firearms registration (serial number) under federal law, and their parts have become more accessible and affordable. This, combined with the increase in law enforcement recoveries of nonserialized and counterfeit firearms in criminal investigations, will most likely create increasing challenges in law enforcement investigations, including weapon accountability access and tracking. PMF awareness and identification can aid PMF recovery, prevention of illicit activities including terrorism, and overall first responder and public safety.
Possession of large amounts of weapons, ammunition, explosives, accelerants, or explosive precursor chemicals could indicate pre-operational terrorist attack planning or criminal activity. For example, in preparation for conducting the July 2011 attacks in Norway, Anders Behring Breivik stockpiled approximately 12,000 pounds of precursors, weapons, and armor and hid them underground in remote, wooded locations.