The weapons usage typology was constructed using information from the questionnaire about the type of weapon most commonly carried or used in the commission of crimes (no weapon, a knife or a club, a handgun, etc.) and for the subset of firearms users, the frequency of criminal weapons use. The inmates were categorized based on information on weapons use in the crimes they committed. "Unarmed criminals" (39 percent) were those for whom there was no evidence that they had ever used any weapons in committing their crimes. "Improvisers" (4 percent) had used weapons in their crimes, but not guns or knives. "Knife criminals" (7 percent) predominately used knives and never firearms in committing their crimes. "One-time firearms users" (14 percent) had committed only one gun crime. "Sporadic handgun users" (14 percent) had used handguns a "few times" but never a shoulder weapon. "Handgun predators" (17 percent) had used handguns many times or most or all of the time in committing their crimes. "Shotgun predators" used shoulder weapons in committing more than one crime. 4 tables.