The Gun Theft Prevention Act strengthens security requirements for federally licensed gun dealers to prevent theft of firearms from their shops. The legislation requires gun dealers to implement specific security measures including locked metal cabinets, safes, video monitoring systems, security alarms, and physical barriers like bollards, with dealers required to submit and annually certify compliance with a security plan. The bill also mandates background checks for gun shop employees, eliminates limits on how frequently the Bureau of Alcohol, Tobacco, Firearms and Explosives can inspect dealers, and requires gun owners to report lost or stolen firearms to authorities within 30 days. The bill establishes a tiered penalty system for non-compliant dealers ranging from written warnings for first violations to license revocation for fourth violations, and authorizes hiring up to 650 additional federal investigators to enforce these requirements. Most provisions take effect one year after enactment, with the Attorney General required to issue final regulations within that same timeframe and submit an implementation report to Congress within two years.