The development of the Darknet as a parallel network to the Web in the 21st century has facilitated illegal trafficking in small arms, as defined by the United Nations. The authors have used investigative research methodologies to observe six weapon sale sites on the Darknet over a six-month period to identify sellers of firearms, the type and caliber of weapons for sale, manufacturer, price in Bitcoin, and the principle national origins of the firearms. This is the first study of its type to explore the illegal sale of firearms on the Darknet. This evidence can be used by law enforcement to intercept and shut down said sites and provide insight to the nature of the illegal arms trade on the Darknet.