Ed Nowicki, who is a POLICE magazine Advisory Board member and the founding executive director of the International Law Enforcement Educators and Trainers Association (ILEETA), believes that one of the biggest problems with the concept of backup guns is that police administrators have a tendency to confuse backup guns with smaller, often less reliable "hideaway guns."
Strictly speaking, a backup gun is a smaller, concealable weapon that can take over the function of a primary duty gun if the larger pistol malfunctions, is lost in action, or is taken away from the officer carrying it. Backup guns are often restricted in caliber by the agencies that permit them. For example, one agency contacted for this article specifies that officers who choose to carry backup weapons must carry a .380, .38 Special, 9mm, .40, or .45.