The Winchester Liberator and Colt Defender were two remarkable shotgun designs that sprang from the fertile imagination of gun designer Robert Hillberg. They were originally conceived as guerilla and counter-guerilla weapons for clandestine warfare, and as such, they were shrouded in secrecy. To appreciate the Hillberg weapons, it is first necessary to consider modern guerilla warfare.
Almost all guerilla warfare is fought by indigenous peoples. Frequently, these people are unfamiliar with modern tactics and are wholly unfamiliar with weapons. As a result, the ideal guerilla weapon must be simple and reliable. More importantly, it must posses a high probability of first round hit and a high probability of a first round kill, even in the hands of a relatively unskilled marksman. The shotgun answers these requirement perhaps better than any other weapon, and the designs proposed by Hillberg brought the shotgun to a new level of refinement for this niche.
Hillberg's first gun was designed around several requirements. Aside from the requirements for hit probability and lethality, it must posses adequate firepower without being too complex. It should also be light and inexpensive to allow it to be delivered en masse via parachute. By early 1962 Hillberg had evolved his concept to a first design. This was a multi-barreled repeating shotgun that was basically an updated pepperbox design. This design gave the firepower of a semi-automatic without the complexity. In the initial iteration, Hillberg envisioned a weapon having four barrel in a diamond configuration, constructed from a simple single casting. His initial design called for an ammunition 'packet' holding four rounds that would be inserted into the gun as a unit, fired, and then ejected by finger pressure.
Early tests proved the worthiness of the design. The concept weapon fired 1.5cm (20ga equivalent) loads and had 4 16.1 inch barrels. The entire weapon was only 8 inches tall, which made for a relatively concealable package that was also maneuverable in tight spaces. It weighed a mere 4 pounds and it's inherent ruggedness made it quite suitable for being air dropped. When Hillberg had completed his initial design and final drawings, he approached Winchester with the proposal of manufacturing the gun. Winchester agreed that the weapon had considerable merit but requested time to study the proposal.
After an engineering analysis, Winchester determined that with a few minor modifications, the weapon could be manufactured for about $20 using the latest casting techniques. Armed with it's own studies, Winchester approached the defense department, and received encouragement fro DARPA, who saw that such a weapon could have vast potential, particularly in Southeast Asia, where the United States was become embroiled. Based on DARPA's encouragement, Winchester decided to go forward, with the new gun being developed under the 'Liberator Project' title, in homage to the gun's intended role, a role filled during the second world war by the Guide Lamp Division of general motors and their 'Liberator' pistol.
During development of the first Liberator guns, it was determined that the ammunition packet possessed certain disadvantages, most notably in size and the difficulty of aligning the packet with the bores. It was also heavy. The ammunition pack that was a salient feature in the Mark I Liberator, was discarded in the later Mark II version in favor of loading individual rounds into each barrel. This had the advantage of eliminating the alignment problem and also led to a two piece, hinge open design that was to prove even simpler to manufacture than the original one piece Mark I.
The basic features of the Liberator Mark II were outlines in a patent granted in 1964 (no. 3,260,009 reproduced here. The weapon features a pivoting breech secured by a stirrup. The was a relatively strong locking mechanism that had been used with much success on pistols of the late 19th and early 20th centuries. The barrels were moved from a diamond patter to a square on to facilitate the tipping breech.
The weapon also features a relatively simple hammer and trigger. The hammer is a simple cylinder with helical cuts and having a fixed striker. Squeezing the full length trigger lever pulled back the striker and caused it to rotate 45 degrees. When the striker was fully retracted, the trigger allowed the striker to fall forward, rotating another 45 degrees and firing one barrel. Pulling the trigger subsequent times rotated the striker 90 degrees and fired the next barrel. This was an eminently simple and robust design that gave the liberator quite respectable firepower. In order to maximize range and lethality, the caliber of the weapon was increased to 16 gauge to take advantage of Winchester's Mark 5 shot collar, which had been developed for the Army's new buckshot ammunition.
Using standard 16 gauge buckshot ammunition, the liberator could easily make multiple torso hits at 30 yards. On average, five hits were obtained at that range, and never less than three.
In order to reduce weight, the Liberator Mark II was cast from two pieces of magnesium, with steel reinforcements cast in place. The whole assembly was coated with an epoxy paint and a removeable shoulder stock was provided. The complete Mark II had four full choke 16 gauge barrels 13.5 inches long. The weapon measured18 inches in length and weighed 7.6 pounds with the shoulder stock.
The completed Liberator Mark II was presented to Winchester in the middle of 1963. It was demonstrated for various military and police agencies who were impressed with it's simplicity and firepower. This was in addition to it's original mission as a 'guerilla gun'. Both Hillberg and Winchester began to see a wider application for their unique shotgun.
As the role of the Liberator was redefined, one featured proved troublesome. While the new shoulder stock allowed for a more stable platform, accurate shooting, particularly with slugs, was made difficult due to the long whole-hand trigger bar. What had been an asset for an insurgency weapon that might be used by someone of poor hand strength precluded the firing of accurate shots. The gun moved to much.
On an earlier design, Hillberg had used a Smith and Wesson handgun frame as a test fixture. Recalling the reduced trigger pull, Hillberg returned to that design. Instead of a heavy revolving striker, the next generation of Liberator, the Mark III, would used a revolver like mechanism with a revolving striker on the hammer which would advance to fire each subsequent barrel. At the same time, Winchester, now completely in charge of the project, elected to make changes in the barrel cluster. There was some difficulty in casting the 4 barrel assembly with the inserts properly located. To simplify manufacture, Winchester instead elected to replace the complicated casting with a simple cluster of four steel barrels held together at the breech. A simple metal plate was welded to the muzzles to alignment and security, and this plate also formed the front sight of the weapon
The Liberator Mark III was only 1/2 an inch longer than the Mark II and weight 7 pounds. In order to widen the appeal, the Liberator Mark III was changed to fire the standard 12 gauge round. The revolver-like trigger was robust and reliable. It could be fired in single action after hand cocking if precise accuracy was required, or it could be fired double action for maximum firepower. Loaded with standard 00 buckshot loads, the Liberator could deliver thirty-six .33 caliber with lethal velocity out to about 60 meters in a couple of seconds. This is a greater volume of fire than the typical sub machine gun. Unfortunately, the military orders that Winchester had hoped for were never forthcoming, and the Liberator failed to catch on with the police market.
The Colt Defender was the logical successor to Hillberg's earlier liberator gun. With the war in Southeast Asia winding down, Hillberg sought to design a weapon that would have appeal to other purchasers - primarily law enforcement agencies. Hillberg believed his initial concept was sound, but sought to increase its versatility. The final design was completed in 1967. In designing the new gun, Hillberg reverted to the 20 gauge 3 inch magnum. He felt that this gave a more compact and easily controlled weapon with nearly identical hit potential and lethality to the 12 gauge. The new weapon was nothing if not visually impressive. Eight 12 inch barrels were joined together around a central axis. The gun possessed the familiar pistol grip revolver action mechanism with a second forward pistol grip for instinctive shooting. Overall length was 17.75 inches with a weight of 8.6 pounds. The weapon was composed of an aluminum alloy receiver with steel inserts and was covered in an epoxy paint finish.
The final version of the weapon was available in four configurations: One version contained a receptacle for a canister of tear gas between the barrels. Pressing the trigger on the foregrip allowed the shooter to spray the target with teargas, giving him a non-lethal option. Another version incorporated a barrel selector on the rotating striker on the hammer. This allowed the shooter to select any one of the eight barrel. This meant that the weapon could be loaded with a variety of ammunition and the shooter could select which round was most appropriate for the situation in question. A third variant include both features, and the fourth had neither.
Like the Liberator before it, the Defender possessed semi-automatic like fire without the complexity of the semi-automatic gun. It was extremely simple to operate and very robust. Hillberg believe that the double action trigger mechanism was ideal for law enforcement applications, as it minimized familiarity and training requirements..
Hillberg thoroughly tested the Defender before seeking out a manufacturer. The design proved to be so correct, that only a couple of minor changes were made for manufacturing.
When Colt Industries was contacted, they showed considerable interest in producing the Defender. However, before committing to production, they insisted on a market survey to see if there was an adequate market for the gun before committing to full production. Colt demonstrated the weapon to a number of departments, and all who saw it were impressed with its compactness, volume of fire and reliability. Additionally, many cited its appearance as having a decidedly deterrent effect.
Unfortunately, the defender was introduced at a time of national recession. Police departments found themselves scrambling to maintain what funds they already had. Despite interest showed in the Defender, Colt determined that there would not be adequate demand for the new weapon to justify full production and the product was shelved. By 1971 the Defender, like the Liberator before it, was dead.
The Liberator and Defender shotguns designed by Robert Hillberg were perhaps some of the most innovative combat shotguns ever devised. Their compactness, reliability, firepower and simplicity have yet to be equalled by any other weapon. They certainly deserved a better fate than they received.