Gun violence continues to be a major crime control problem in many metropolitan cities in America. To comprehend this problem more completely, this study seeks to develop an understanding of the dynamics of illegal firearm markets in one particular city: Milwaukee, Wisconsin. In particular, the characteristics of guns and gun buyers that are related to fast firearm time-to-crime are identified. The U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) trace data and Milwaukee (Wisconsin) Police Department (MPD) records associated with guns purchased at federally licensed gun dealers and subsequently confiscated by the MPD in 2005 (N = 1,563) are used. The results of the analyses revealed both the characteristics of the fast time-to-crime guns (large caliber, semiautomatic, sold at a particular Milwaukee gun dealer) and their buyers (minority females). The results highlight problematic gun sales and purchasing patterns that are suggestive of statutory changes, stronger regulatory measures, and supply-side gun market disruption efforts.