This bill creates a new federal crime targeting mass shootings involving machineguns or certain semiautomatic weapons, with mandatory prison sentences ranging from years to life imprisonment. The law applies when three or more people are killed in a single incident with these weapons and the crime involves interstate commerce, interstate travel, or occurs on federal property. The bill defines "covered semiautomatic weapons" broadly to include various rifle and shotgun models with certain features like pistol grips, adjustable stocks, or magazines holding more than a specified number of rounds, as well as any weapon the Attorney General determines is substantially similar to those listed. The legislation also requires the Department of Justice to submit annual reports to Congress detailing charges filed under this new law, including information about the defendants' demographics and weapons used. Additionally, the bill mandates that demographic data be included in federal wiretap reports involving arrested individuals.