According to ATF, five systems and one subsystem contain data that readily identify retail purchasers of specific firearms. The GAO reviewed the ATF's Out-of-Business Records System and Multiple Sales System. These systems play a significant role in the firearms tracing process, contain data obtained from non-law enforcement sources, and involve large numbers of records and reports containing data on firearms transactions and purchases. The Out-of-Business Records System contains records that Federal firearms licensees are required by statute to forward to ATF within 30 days following a permanent discontinuance of their business. The National Tracing Center microfilms and indexes these records to facilitate locating them for firearms tracing purposes. The Multiple Sales System contains data from reports that Federal firearms licensees are required by statute to send to ATF showing sales or other dispositions of two or more pistols and/or revolvers to an unlicensed person at one time or during any five consecutive business days. The GAO review indicates that both systems comply with data restrictions, that the systems do not violate the appropriation rider prohibition against consolidating licensee records, and that the ATF appropriately operates both systems. Appendixes contain additional information on the disposition of pistols and revolvers, a legal analysis of statutory restrictions on Federal firearms licensee data, and ATF comments on the GAO review. 8 tables and 2 figures