The main purpose of the Stop Arming Cartels Act of 2025 is to enhance public safety by prohibiting the importation, sale, manufacture, transfer, or possession of .50 caliber rifles. This legislation aims to address concerns about the use of these powerful firearms in criminal activities, particularly by drug cartels and other organized crime groups. Key provisions of the Act include a complete ban on .50 caliber rifles, with specific exceptions for government entities and for individuals who lawfully possessed such rifles before the law was enacted.