This proposed legislation aims to regulate certain firearms and ammunition feeding devices. It introduces comprehensive definitions for "semiautomatic assault weapon," encompassing rifles, pistols, and shotguns based on specific functional and cosmetic features, as well as an extensive list of named models and their variants. Additionally, the bill defines a "large capacity ammunition feeding device" as any device capable of holding more than 15 rounds, excluding certain .22 caliber rimfire tubular devices. Under this bill, it would become unlawful to import, sell, manufacture, transfer, or possess these newly defined semiautomatic assault weapons and large capacity ammunition feeding devices in interstate or foreign commerce. However, the legislation includes a significant grandfather clause , allowing individuals to retain possession of such items that were lawfully owned prior to the bill's enactment. Several other exemptions are provided, including for manually operated firearms, permanently inoperable weapons, antique firearms, and those firing only rimfire ammunition. The ban does not apply to government agencies, qualified law enforcement officers (both federal and state, on or off duty), campus law enforcement, and certain licensees under the Atomic Energy Act for security purposes. Retired law enforcement officers are also permitted to possess these weapons under specific conditions. Licensed manufacturers and importers may possess them for authorized testing or experimentation, and a detailed Appendix A lists numerous specific rifles and shotguns that are explicitly exempted from the ban. The bill also introduces new requirements for grandfathered semiautomatic assault weapons, mandating secure storage or safety devices if they are accessible to individuals legally prohibited from owning firearms. New semiautomatic assault weapons and large capacity ammunition feeding devices manufactured after the enactment date would be required to bear serial numbers and manufacturing dates. Violations of these new prohibitions would be subject to federal penalties, and existing provisions for firearm seizure and forfeiture would be expanded to include these newly regulated items. Significantly, the legislation mandates background checks for the private transfer of grandfathered semiautomatic assault weapons between unlicensed individuals, requiring a licensed dealer to facilitate such transactions. Temporary transfers for target shooting at licensed facilities are exempted. Finally, the bill authorizes the use of Edward Byrne Memorial Justice Assistance Grants to fund voluntary buy-back programs for semiautomatic assault weapons and large capacity ammunition feeding devices.