The centenary of the Thompson gun
Richard Barnes reviews the history of this iconic weapon
Richard Barnes reviews the history of the development of this classic weapon which started in the trenches of WWI where traditional rifles were to large and slow firing to be effective.
During World War I, General John Taliaferro Thompson, a distinguished Ordnance Deptartment officer who retired a few years prior to America’s entry into the war, believed the realities of trench warfare were simply too much for the technology of the time.
Up until World War I, guns had been developed based on the idea of the traditional European battlefield, with tightly choreographed regiments of soldiers marching in formation, all firing in unison. Firing quicker was an interesting concept, but despite Maxim’s machine guns being produced since 1889, it was only recently that they had been adopted in large numbers by the armies of the world. However, when the powderkeg of Europe touched-off, the primary weapon in the hands of the soldier was still a bolt action rifle designed for pitched battles in open fields. What they found instead was that their accurate long-range rifles were simply too big and too slow to be effective in the confines of an enemy trench.
Following the Spanish American War of 1898, John T Thompson, had gained experience in the development of firearms from when he had been appointed as chief of the Small Arms Division for the Ordnance Department. There he was instrumental in selecting the .45
ACP cartridge and he also oversaw the development of the US Army's Springfield
M1903 rifle and the adoption of the iconic Colt 1911 pistol. The self-loading, or automatic, rifle intrigued Thompson, although none of the existing types of actions met his critical approval. The Browning Automatic Rifle, model 1918, was a moderately successful gun, but one of its disadvantages was it was too heavy. Indeed, John Thompson believed that a gas and piston-operated weapon, which most machine guns of the time used, was not practical due to its complicated structure.
John T Thompson is quoted as saying that the average soldier required a weapon that was, “Compact enough to not get tangled up when fighting in a trench, but accurate enough to hit targets some distance away. It needed to fire multiple rounds of ammunition in quick succession, but remain simple
enough, so that the average soldier could clean it and disassemble it, without losing the important parts in the mud of France. It needed to have minimal recoil, but capable of producing enough firepower to kill the enemy, it needed to be perfect.”
He therefore decided to develop a lightweight automatic rifle, which was simple to operate and maintain with a positive action under all conditions, but lightweight with a high rate of controlled fire.
While carrying out research for his project, to allow his revolutionary design to operate safely, without the complexity of a recoil or gas operated mechanism, John T Thompson came across Patent No. 1,131,319 at the US Patent Office: ‘A Breech Closure for Firearms’, granted to a retired US Navy Commander, John Bell Blish in 1915. The Blish principle was based on the adhesion of inclined metal surfaces under pressure. Blish noticed that some of the Navy's breech loading heavy guns, breech blocks, became unscrewed when they were fired with a light load, while larger loads producing more pressure held a tighter seal. He attributed this to the different metals used in the breech and breech block. He believed that under great pressure, two different metals could adhere together better than two pieces of the same metal. He called it the Blish Principle, around
which he designed a breech block which could be used in small arms.
John T Thompson discussed his ideas with John Blish, who was excited about his invention being incorporated into the new gun, so an agreement was struck between them. All that was lacking now was the finance to complete the project, but John T Thompson found financial backing for his idea from the aptly named tobacco tycoon, Thomas Fortune Ryan and in 1916 they founded Auto Ordnance Corporation (AOC).
The development
John T Thompson proceeded to assemble a talented team and established the AOC engineering department in Cleveland, Ohio, to work with the Warner-Swasey Company to develop his automatic rifle design. The new weapon was to be developed for the military .3006 round, which was used in the Springfield M1903 rifle.
The principal designers were Theodore H Eickhoff and Oscar V Payne, whose names appeared on most of the patent applications. This team provided the expertise for the AOC to develop, unintentionally, the first American submachine. The Engineering Department worked for two years, with only limited success in developing an automatic rifle, discovering a series of problems with the Blish Locking System.
The design used a small bronze H-shaped block, fitted into the gun's steel bolt, which according to the
Blish Principle would slow the bolt's recoil. Scientifically, it is claimed by some, the Blish Principle of metal adhesion does not exist.
By late 1917, the limits of the Blish Principle were discovered. Rather than working as a locked breech, it functioned as a friction-delayed blowback action. During one of the tests, it was discovered that the .45 ACP cartridge was the only cartridge in US service, which could function flawlessly with the system.
This discovery forced the team to review their plans and Eickhoff travelled to Washington to break the news to John T Thompson, who had been recalled to active duty earlier in 1917. Thompson’s reply to the news he received concerning the discovery, was quoted by Eickhoff as, “Very well we’ll put aside the rifle for now and instead build a little machine gun. A one-man, hand-held machine gun, a trench broom!”
Upon Eickhoff’s return to Cleveland, the team began designing a one-man, hand-held machine gun in .45 ACP. The idea was to develop, what was nicknamed a trench broom, for use in the ongoing trench warfare of World War I. However, delays in the development, resulted in them missing the target market, as the Armistice was signed on 11 November 1918, and the revolutionary design missed the opportunity to prove itself in combat.
It was not until 1919 that the development phase began, during which, it is believed AOC produced at least 40 Model of 1919s. This was more an evolutionary series, than a model. Each serial numbered receiver, being a slightly
modified version of the proceeding receivers, to resolve issues with the design. These resulted in a perfect model being selected, as the basis for the Model of 1921.
The Model of 1919s are divided into two different series of designs, with the second series divided into four models, each subsequently divided into several sub-model designs.
Some of the experimental models fired over 1,500 rounds per minute (rpm), and early literature and advertising quoted this rate of fire as standard for full-automatic fire. Even when the rate of fire was eventually reduced to 800 rpm, it would still empty a 20-round magazine in just 1.5 seconds. Therefore, the AOC team had to find a suitable high-capacity feeding device for the weapon, so the design of the drum magazine ran concurrently with the weapon. This became part of the famous silhouette of the Thompson.
The first Model of 1919 was called the Persuader. This Thompson was designed to fire .45 ACP cartridges from a cloth belt of ammunition. However, the design proved to be an unreliable means of supplying the rapid-firing design. At best, only seven rounds could be fired, before a malfunction of the feed system, stopped the action.
So, running concurrently with the design of the Model of 1919, was the research to find a suitable loading device. They required was some sort of container holding the ammunition, which fed them directly into the weapon.
In 1919, after tinkering with an idea to use a cartridge belt inside a magazine to feed the rounds into chamber, Oscar Payne, developed a staggered two column position feed magazine, designing the 20-round XX box magazine. This was the first use of the double-column/dual-feed magazines, which are now quite common.
His next challenge was the development of a high-capacity magazine, which he did, producing the classic Thompson drum magazines, which would become an integral a part of the Thompson image.
The drum design and the second series of Model of 1919s, known as the Annihilators, were developed simultaneously. The first Annihilator was a work bench model of the proposed, Annihilator Trial Mechanism. This was used to validate a design based on improvements to the Persuader. The Annihilator I, Serial Number 1 Model of 1919 was the first Thompson design, to feed ammunition from a drum and a box magazine.
These evolved into the Annihilator II,
Serial Numbers 2 and 3, Model of 1919s. These were the first Thompsons to be demonstrated to the New York City Police department, (NYPD) in March of 1919, Serial number 2 test firing 18,000 rounds, without a stoppage.
Further modifications were made which resulted in the Annihilator III. This model is divided into at least five separate sub-model groups. The first of these groups was the Annihilator III, Model Cs, of which there were originally 10 sets of components built, but not all were assembled into Model Cs.
Only two known Model C, 1919s are known to exist today, Serial Numbers 6 and 7.
The final sub-model group of 1919s were the Model G Annihilator IIIs. These were the first 1919s to incorporate a round bolt face, centred actuator (bolt handle) and a redesigned firing pin system, providing improved reliability.
The Development Model of 1919s had no stock or sights and only functioned as a fully automatic weapons, firing
Colt .45 ammunition, although other ammunition types were tested. The weapon could be fired while aiming
down the barrel, but the absence of the stock is explained by the fact when clearing a trench, point shooting from the hip was a more effective method, which was the original idea behind the weapon.
In the final design of the Model of 1919, the AOC design team had introduced three mechanical principles, to produce a lightweight, relatively speaking for the time it was invented, simple to operate weapon, combined with sturdiness and reliability. The engineering features introduced in the revolutionary design, were the Blish breech locking system, the oiling device and the new drum magazine to feed the weapon.
General Thompson was keen to proceed with marketing his idea and in August 1920, a prototype Model of 1919 Submachine gun had its first public demonstration at the National
Rifle Matches at Camp Perry, Ohio. Everyone who witnessed the gun in action was amazed at its compact size and massive firepower. The prototype gun demonstrated, firing at a rate of about 1,500 rounds per minute, could empty a 100 rounds drum in four seconds. At this rate, the sound was described as like the loud ripping of a rag.
In preparation of the production of the new weapon, the AOC board of Directors elected to change the name, from the aggressive Annihilator, to one suitable for marketing the product. General Thompson wanted something that would distinguish the weapon from its larger bulky machine gun predecessors. They considered the terms ‘Auto gun’ and ‘Machine Pistol’, but finally came up with the phrase ‘Submachine gun’. This was to denote a small, hand-held, fully automatic firearm that was chambered for pistol ammunition.
The board voted to add another word to the name, to honour the key player in its creation, so it was officially renamed the Thompson Submachine gun.
The Thompson was the first weapon to be called a submachine gun (in fact, as point of trivia, it was the early AOC advertisements that established the style submachine gun, rather than submachine gun).
It took a few years for the Thompson submachine gun design and name to emerge, and once it had, AOC remained a one-product company.