There is one more interesting single shot pistol which saw a lot of production during World War II. This was the FP-45 Liberator, which was produced in the United States during WW-II.
This pistol was designed in 1942 and hence it also has the designation M1942. The purpose of this design was to make a basic pistol that was very cheap to manufacture and easy to mass-produce and could be dropped in large quantities over Europe to arm the resistance forces. The Liberator was also designated as "Flare Projector" Caliber .45 (FP-45). The .45 was because it fired a standard 45 caliber pistol bullet (the same as that used by the Colt M1911 automatic pistol). The "Flare Projector" designation was deliberate misinformation, to disguise the purpose of this project and the fact that this weapon was mass-produced. The original design documents also had mislabeled parts to hide the true purpose of this device. For instance, in the original design documents, the barrel is called "a tube", the trigger is called "yoke, the firing pin is a "control rod" and trigger guard is a "spanner".
The pistol had only 23 parts, most of which were stamped or turned steel components, which made it very easy to manufacture. The barrel was completely unrifled, so it wasn't accurate beyond 10 meters or so. The pistol was packaged in a cardboard box along with 10 bullets and a comic-book style instruction sheet on how to use the weapon. There was also a wooden dowel included in each box to push out the fired cartridge case. It took approximately 10 seconds to load this pistol. Extra bullets could be stored in the handle of the pistol.
This weapon was never designed with regular troops in mind. It was designed to be mass produced and cheap, so that large quantities could be dropped over occupied Europe. It was also designed to be concealable. The idea behind this weapon was that a resistance fighter could use it at close range to surprise and shoot an enemy soldier and then take his weapons.
Manufacturing was outsourced to the Guide Lamp Division of General Motors. Guide Lamp Co. used to be an independent headlight manufacturer before it was bought by General Motors in 1928. During World War II, the Guide Lamp division also produced small arms, notably the famous M3A1 "Grease Gun" submachine gun. General Motors produced over one million of these pistols over a 6 month period, at an average cost of $2.40 per weapon (or about $30 in 2010 dollars). Actual production time in the 6 month period when this pistol was made was actually only 11 weeks and the entire weapon was produced at a rate of one every 7 seconds or so. This meant that this weapon had the dubious distinction of having a faster production time than the time taken to load it!
Despite its original intention, the weapons were not mass-dropped over Europe. More of these were dropped into China and the Philippines during World War II. The same concept was revived during the Vietnam war, when the Deer Gun (another low cost weapon made of Aluminium) was designed in 1964 for similar purposes. The Deer Gun was never distributed in large quantities though.
Even though the Liberator originally cost $2.40 to produce and there were over a million of them manufactured, it is something of an expensive weapon today in auction houses. In fact, a Liberator in its original box with instruction sheet can cost over $2000 at current day prices!