Thompson sub-machine gun …or STEN?

The men in control of the 19th century’s armies were, at best, a conservative bunch. Military thinking during that period always found innovation of any sort difficult and nowhere was this predilection so marked as in the area of repeating rifles.

The British Army did not introduce a magazine rifle until 1888, when the Lee-Metford, with a magazine holding ten rounds, began its service life. Unfortunately, the Metford’s barrel was not suitable for the new smokeless ammunition then being introduced, and the rifle began to be replaced in 1895 by the Lee-Enfield, a weapon which will be familiar to many both in and out of Britain’s armed forces. The Army Command was concerned about soldiers issued with a magazine rifle wasting ammunition however, so the Lee-Enfield was fitted with a magazine cut-off to allow the rifle to be loaded with a single cartridge between shots, thus conserving the contents of the magazine.

The US army also suffered from a tendency amongst its senior officers to be unreceptive to new ideas and it was not until 1892 that the single-shot Springfield was wholly replaced with the Krag-JDrgenson rifle, which featured a five-round magazine amongst its other improvements. By the time America was involved in WWI, its troops had been equipped with a replacement for the Krag, the excellent Springfield Model (M) 1903. Unfortunately, although both the M1903 Springfield and Lee-Enfield were excellent weapons, their long barrels proved a cumbersome liability at close-quarters in the trenches. Something different was needed and, fortunately for its soldiers, the American Army had in General John Thompson, its Chief of Small Arms for the Army Ordnance Department, a man who was clear about the shortcomings of conventional rifles … and not afraid to say so.

The Thompson sub-machine gun: ‘A one-man, hand-held machine gun’

What was needed for trench warfare, according to General Thompson, was: ‘… a small machine gun, a gun that will fire 50 to 100 rounds, so light that he can drag it with him … and wipe out a whole company single-handed. A one-man hand-held machine gun Thompson had left the Army in 1914, upon the outbreak of World War I in Europe and, in 1916, he and his son began a firearms manufacturing company which they called the Auto-Ordnance Corporation. He was recalled to the Army in 1917, with the rank of Brigadier General, and appointed to serve as Director of Arsenals.

By now thoroughly dissatisfied with the performance of the standard military rifle as a weapon for trench warfare, he gave orders to his staff at Auto-Ordnance to begin development of a new, hand-held automatic rifle, using the .30-06 US Army cartridge. Unfortunately, problems with this powerful military round meant that the new weapon, now chambered for the .45 Automatic Colt Pistol (ACP) cartridge, did not begin production until March 1921. It was named the Thompson and designated a ‘submachine’ gun, because it used a pistol cartridge, which was shorter and less powerful than the standard rifle cartridge, although it was of a larger calibre and later proved to have at least as much stopping power. These first weapons were produced by the Colt Patent Firearms Co. at their Hartford factory and are known to collectors as the ‘Model of 1921A’ or M1921 A.

Like most innovative designs, the Ml921 A had its problems, one of the most significant being its tendency to rear upwards when fired on fully automatic. This problem was alleviated, if not fully cured, by the development of a ‘compensator’ by Col Richard Cutts, which could be simply screwed on to the muzzle of a standard Thompson, without any modification. The compensator had four vent slots in its top surface through which the muzzle gases were expelled, causing a significant downdraft and counteracting the new machine-gun’s tendency towards ‘muzzle-lift’ when firing.

A new version of the ‘Tommy gun’, the M1928, was introduced in 1928, with a lower, more controllable rate of fire, 600 rounds per minute (RPM), as opposed to the 800 RPM of the Ml921. It was that Model which was accepted into US Navy service with the Marine Corps in 1932 and sold subsequently in small numbers to the military and civilian users.

The outbreak of WWII in 1939 and in particular British materiel losses at Dunkirk, meant an increased demand for small arms. As Colt had by this time ceased production of the Thompson, the new owner of what was now called the Thompson Automatic Arms Corporation, one Russell Macguire, approached the Savage Arms Corporation with a plan to offer them a licence to manufacture the weapon. After some very careful negotiation (Macguire’s slightly unsavoury reputation apparently having preceded him). Savage agreed to produce the Thompson, with Remington also responsible for a number of parts, in particular the barrels and wooden stocks. Production began in May 1940 with a Thompson designated the M1928A1, and this weapon underwent a number of changes in the period between 1940and 1942, mostly associated with simplifying production and reducing costs, before being accepted by the US Army Ordnance Board as ‘Gun, Sub-machine, Caliber .45, Thompson, Ml’. A later, simplified variant was designated the Thompson M1A1. Levels of production required to supply the US Army with the new gun were so high that a new Auto-Ordnance factory was opened in Bridgeport, Connecticut, in January 1941 and most later Thompsons were assembled here, although Remington still made the barrels, stocks and many internal components.

The Ml/Al was the last Model to be manufactured, production ending in 1944, after nearly 1.4 million guns had been produced.

Thompson Model specifications Model 1921 A

This was the first production Model of the Thompson, using the complex Blish lock, and manufactured exclusively by the Colt Patent Firearms Company of Hartford, Connecticut. All Models of the Thompson are capable of semi-automatic and fully automatic fire. Characteristic features include:

A barrel with deep cooling fins, a blade foresight and Lyman ‘ladder-pattern ‘ rear sight, a central, cocking lever with a milled centre slot and front and rear pistol grips. A fire-selector switch and safety lever were fitted on the left side and the receiver is machined to accept a drum magazine. Serial numbers were stamped on the left side of the magazine receiver, on the frame under the detachable butt and on the barrel under the foregrip.

Rate of fire was 800 RPM.

The right side of the frame bears patent information and the stamp:


The left side of the frame is stamped:


MODEL OF 1921,

NO. XXXXXX ‘XXXXXX’ denotes the serial number:

Some of these early weapons were converted to operate only in semi-automatic mode.

The finish on all these weapons is a deep blue with American walnut stocks.

Model 1921 AC

Thompsons made from 1927 were all fitted with a Cutt’s compensator to make them easier to control when used in automatic fire mode. They were designated Ml921 AC and are similar to the original Ml921 in all other respects.

Model 1928

This group of guns includes the 1,500 first accepted into US Navy service, (for the Marine Corps) on 14 March 1932, designated ‘Gun, Submachine, Caliber .45, US Navy Model of 1928’. It is similar in outward conformation to the M1921A and M1921 AC, but with a riveted steel block on the actuator and smaller recoil and buffer springs, designed to slow the rate of fire to a more manageable 600 RPM.

‘Postal Service’ Thompsons

Prior to acceptance by the Navy, 200 Ml921A Thompsons were sold to the US Marine Corps, who were assigned to protect the trains of the US Postal Service after a series of violent robberies in 1926. The guns were later converted to use the M1928 mechanism and the original ‘ Model of 1921’ mark on these guns is over-stamped ‘1928’.

Model 1928A1

This group of Thompsons marks the beginning of the Savage Company’s involvement with Thompson manufacture and they characteristically bear an ‘S’ prefix to their serial numbers, most components also being stamped with an ‘S’. In all other respects they are exactly similar to the Model 1928 Thompsons produced by Colt, although some have a grey ‘Parkerised’ finish rather than being blued.

The right side of the receiver bears patent information and the stamp:


The receiver is stamped on the left side:

US MODEL OF 1928 A1 NO. S-XXXXXX ‘XXXXXX’ denotes the serial number.

Above the rear pistol grip, also on the left side, is stamped:


Thompsons made by Savage between 1940 and 1942

Although the M1928A1 and M1A1 are seen by collectors as distinct weapons, the final, definitive version of the M1A1 was not really in production until late in 1942. In the intervening period Savage introduced a number of modifications and improvements and guns were produced with new components fitted as and when they became available, rather than as part of a coherent process of improvement. This means that perfectly authentic, ‘hybrid’ guns may sometimes be encountered fitted with components not usually thought to be characteristic of a particular Model.

Production of the Thompson was begun in a new Auto-Ordnance factory in Bridgeport, Connecticut, in January 1941 and weapons made in this new facility bear the appropriate factory stamp.

Model Ml

This is the Thompson most commonly carried by Allied troops in WW 2. Externally, it differs from the Ml 928A1 in having a simple horizontal foregrip, with a groove on both sides, a non-adjustable rear sight and a barrel without cooling fins. The position of the cocking handle was also changed from the top of the receiver to the right-hand side and the fire-selector and safety levers were changed to rotating studs.

The right side of the receiver bears patent information and the stamp:


Later weapons may be stamped:

AUTO-ORDNANCE CORPORATION BRIDGEPORT, CONNECTICUT, U.S.A. The receiver is stamped on the left side:

US MODEL OF 1928 A1 NO. XXXXXX ‘XXXXXX’ denotes the serial number.

Above the rear pistol grip, also on the left side, is stamped:

THOMPSON SUBMACHINE GUN CALIBRE .45 AUTOMATIC CARTRIDGE Later weapons may bear a simpler stamp on the left side, which includes the serial number: THOMPSON SUBMACHINE GUN CALIBRE .45 Ml NO. XXXXXX

Internally, the mechanism was greatly simplified, the complex and hence expensive Blish lock mechanism being eliminated and the breech-block and recoil spring being redesigned, so these weapons now had a relatively simple, open-bolt ‘blow-back’ mechanism, similar to the British Sten. Model Ml Thompsons all have a grey ‘Parkerised’ finish, with a stock and foregrip of a cheap hardwood rather than polished American walnut.

These changes brought the unit price of an Ml Thompson down from $ 225 (£56) to $44 (£11)-

Model Ml/Al

Externally similar to the Ml, in this Model the breech-block and firing pin are in one piece, replacing the ‘floating’ firing pin of the earlier Ml.

Britain and the Thompson

Agents of the British Purchasing Commission placed their first order for a number of Ml928

Thompsons in February 1940, with total British orders eventually rising to 514,000. Guns intended for transport to Britain bear the stamps of British Ordnance inspectors, although many guns bearing these marks were never sent overseas.

By April 1942, only around 100,000 of the guns which had been ordered had arrived in the UK. By now, however, the need for small arms had become so desperate that the Royal Small Arms Factory, Enfield, had produced a lighter, cheaper machine gun of their own design, the Sten, and it was this weapon that was issued to the majority of British and Commonwealth units. Thompsons were still issued to Commando units and, rather surprisingly, the Home Guard, as they became available.

The Sten gun

Produced in the aftermath of Dunkirk to replace the huge numbers of weapons lost during the evacuation, the Sten sub-machine gun was the brainchild of Major R.V Shepherd OBE and Mr Harold Turpin, its name being an acronym composed of the initial letters of the inventors’ surnames and ‘EN’ from Enfield.

In common with the Thompson Ml and Ml/Al Models, the Sten was a simple, open-bolt, blow back design, with a fixed firing pin on the face of the bolt. Cocking the weapon involves simply drawing the bolt to the rear of the cocking lever slot, against the action of the mainspring, where it is retained by the trigger sear. Squeezing the trigger releases the bolt, which is driven forward by the main spring, stripping a round from the magazine, chambering and then firing it all in the same operation, the weapon continuing to fire until the trigger is released or the magazine is empty. Rate of fire was approximately 550 RPM, which means a 30-round magazine was emptied in approximately three seconds. Operation of the fire control button, sited just above the trigger, switched the mechanism to semi-automatic.

The Sten’s design has a number of advantages: the firing chamber remains empty until the trigger is pulled, which means there is no possibility of a round being discharged through over-heating (known as ‘cook-off’ to the infantryman), the open ejection port allows increased air flow to cool the mechanism and manufacture was cheap and relatively simple. Unfortunately, this simplicity, together with the 9mm pistol ammunition it was chambered for, brought its own disadvantages, most notably a severely restricted accuracy, effective range being barely 100m.

Cheapness and speed of manufacture had to be the inventors’ main concerns, with Britain in such desperate need of weapons, and it is perhaps surprising that they managed to incorporate these characteristics into a submachine gun which, on the whole, performed remarkably well. Its assembly only required minor welding of simple parts stamped from sheet metal, with only minimal machining being required for parts such as the bolt and main and trigger springs. Later developments centred around simplifying the manufacturing process and reducing costs even further, rather than improving performance, and these measures were so effective that one of the later variants, the Mk III, could be produced in five man-hours for just over -£2.

Between 3.6 and 4.7 million Stens had been manufactured by RSAF Enfield and other sources by the time the British Army began replacing them with the Sterling sub-machine gun in 1953.

Sten specifications Mark I

This first model Sten was characterised by the use of wood for the construction of the fore-grip, forward handle and part of the stock. The design also incorporated a clumsy flash-hider and the barrel sleeve (or shroud), which had three small holes in the top, extended all the way to the end of the barrel, unlike the succeeding weapons in the series. Production was approximately 100,000 weapons.

Mark I*

A simplified version of the Mark I, with the foregrip, wooden furniture and flash hider omitted.

Mark II

The most common variation, this type differed from the Mark I in having a removable barrel which projected beyond the barrel sleeve, which was shorter than the Mark I and with three sets of holes equally spaced around the circumference. A Canadian variant of the Mark II, fitted with a ‘skeleton’ type butt, and a suppressed (silenced) version, the Mark IIS, were also produced.

Total production of the British-made guns was approximately 2 million weapons.

Mark III

The most simplified of the war-time designs, and the gun with the biggest production numbers after the Mark II. It was characterised by a magazine receiver, ejection port and barrel sleeve constructed in one piece, the barrel projecting only slightly past the muzzle end of its sleeve.

Mark IV

A smaller, lighter variant intended for use by airborne troops, which never progressed beyond its initial prototype.

Mark V

Produced in 1944, when the threat from Nazi Germany was less immediate, these were a better quality version of the Mark II, with a wooden pistol grip, fore grip and stock. A No 4

Lee-Enfield foresight and a bayonet mount were also fitted.

Mark VI

A suppressed (silenced) version of the Mark Y the clumsy suppressor increasing its weight from seven to nearly 10 lbs.

The men who used the guns

It has come to be widely accepted as fact that all the men who used Shepherd and Turpin’s ‘Woolworths gun’ loathed it, so it may come as a surprise to know that, in fact, many preferred it to the much heavier Thompson.

True, the Sten had faults. It had to be kept clean or stoppages would occur due to dirt on the face of the breech, in the bolt raceway or in the chamber itself. Magazines could be temperamental and had to be loaded and fitted carefully, the poorly tempered springs in the magazines of early weapons being cited as a particular problem (experienced users tended to load magazines uith only 25-27 cartridges, rather than standard 32 rounds). In addition, hands had to be kept well clear of the cocking lever slot, or the result might be a severed finger or thumb. And of course, in earlier Mks, the simple, open bolt, blow-back mechanism was prone to firing if dropped or handled carelessly.

The Sten was not alone in having problems, however. Thompsons were also prone to stoppages, especially if poorly maintained or the subject of heavy use, and the complex mechanism would quickly jam if dirt or mud was introduced into it. They were heavy, IOV2 lbs compared to the 7 lb Sten, and Resistance fighters also found them hard to conceal. In particular, they were at an especial disadvantage in desert environments, like the North African theatre. Here, their carefully lubricated mechanism attracted dust and sand, a combination which formed a perfect grinding paste and wore out the guns’ precisely machined components in an incredibly short space of time. The Sten, which had no fine tolerances inherent in its mechanism and was fired without lubrication, proved much more useful and reliable in the desert. Allied armourers certainly learned from their units’ experience with the Thompson, however, subsequently modifying them to prevent the egress of sand and issuing them free of lubricant. Guns subjected to this treatment then worked reliably, without any of the previous refinements.

Stens also possessed another significant advantage, in that they were chambered for Luger’s 9 x 19mm Parabellum cartridge, the same ammunition as the German Army’s Luger pistol and all of its issue sub-machine guns, such as the MP34, MP35 and MP38/40 variants. This made it very convenient for Resistance groups, who could replenish their supply of cartridges from the enemy’s own ammunition pouches.

Perhaps most importantly for the British was the question of cost. RSAF Enfield and its subsidiaries were finally able to make a Sten for as little as -£2, whereas in November 1940, the cost of manufacture was such that the Americans were selling the Thompson to Britain for £27.50 ($ 110) each. This was in fact, half what they had been asking for smaller quantities in January 1940, although by August 1942, the new Auto-Ordnance factory was able to offer the new Ml / A1 to the British for a unit price of just -£l 1 ($ 44) (PRO document WO 185/12).

In spite of its disadvantages, the Sten was undoubtedly the way forward for the future of military firearms. The Thompson was beautifully made, finely machined, everything a 19th -century gun owner was looking for. Unfortunately, it was not private gun ownership that counted here but military contracts, and the military were perfectly happy with a cheap gun that wore out in a reasonable length of time, rather than something like the Thompson, which would last indefinitely. In reality, military purchasers both during and after WWII much preferred a cheap gun with a limited service life, because the rapid progress in firearms’ design and development meant that an infantry weapon was out of date and needed replacing after a much shorter time interval than had been the case in thel920s and 30s.

Functional guns like the British Sten, the German MP38/ 40 and the American M3 ‘Grease Gun’, with their cheap pressed steel construction, would be the forerunners of the new generation of military weapons, while the rigorous construction techniques which had produced the Thompson, the Springfield Ml903 and the Lee-Enfield would survive British-made Sten Mk II, showing the frame stamps, the ‘ENGLAND’ stamp implying that this was its place of manufacture. Courtesy of James D. Julia Auctioneers only in the world of the hand-built sporting gun, available to those who could afford the luxury of Purdey or Westley-Richard’s superb products.

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