The Thompson Submachine Gun Read online

  We found the belt to be impracticable and abandoned it altogether ... we had become accustomed to keeping the weight of parts to an absolute safe minimum, so quite naturally we also designed the machine gun as light as possible. Finally we came to the conclusion that the gun parts were entirely too light and movement of parts entirely too fast to drag into position a belt of heavy cartridges. We decided to wipe the slate clean and start all over again.

  The prototype ‘Persuader’ showing the basic shape that would evolve into the familiar Thompson.

  The ‘Annihilator 1’ was the first prototype incorporating a more ergonomic front and rear pistol grip layout with top mounted actuator, or cocking handle.

  Cooling of the barrel was a problem, and the finning first appeared on the Model 1919 ‘Annihilator II’. Note the slots in the magazine well to accommodate a drum magazine.

  Work began anew in late 1917 on an improved design, but it was not until 1919 that a working variant was manufactured. This weapon bore many of the hallmarks of the later guns – a slab-sided receiver, rear and forward pistol grips, modified Colt M1911 box magazine and topmounted cocking handle – and was known as the ‘Annihilator’. There were many alterations made to the original design. It had a square bolt and the actuator, or cocking handle, was offset and machined in one piece with the firing pin, but it could only be fired in full-automatic mode. This new design posed a problem with regard to ammunition supply, as its rate of fire was a heady 1,500rpm and the Colt magazine held only seven rounds. Furthermore the barrel had no cooling fins fitted, vital on a weapon capable of such a rate of fire. In an attempt to solve the ammunition supply problem, a drum magazine holding 50 rounds was produced, and two more guns were manufactured. These second-generation guns also sported finned barrels, a removable front grip and the receiver was machined with slots for insertion of the drum magazine. Curiously, no butt was fitted, the gun quite literally being a ‘machine-pistol’. There was not even provision for a fore-sight, but the weapon was gradually taking on its own momentum, as parts of the guns were slowly modified and adapted to improve function and reliability. One area in which significant improvements were made was in the magazines, as a 20-round box pattern was produced as well as two drums, holding 50 or 100 rounds and named ‘L’ or ‘C’ pattern respectively (these being the Roman numerals for 50 and 100). Further additions to the original design included a selector switch for full- or semi-automatic fire, a rounded cocking handle set centrally into the top of the receiver and a simple blade fore-sight. Altering the angle of the Blish lock helped slow things down somewhat but the rate of 800 rpm was still high. By the end of 1918, some 24 guns had been constructed. (A number of guns with no serial numbers have surfaced over recent years, so the actual total weapons made may be as high as 40.) These early weapons were known as the M1919 and the series was used as a rolling test-bed to smooth out the rough mechanical edges and ensure the basic concept was sound. Both Payne and Eickhoff were satisfied that the gun was practical, but it still needed to be simplified to ensure the least number of working parts for both reliable functioning and ease of manufacture. There was little that could be done to reduce the high machining costs, despite the fact that the final variant of the M1919 comprised only 11 major component parts, and Auto-Ordnance desperately needed orders. The time had come to put the gun into production.

  Two New York City policemen pose for a publicity photo with M1919 ‘Annihilator III’ Thompsons.

  Making the gun was all very well, of course, but it still lacked a name and any model designation. It was still, strictly speaking, a machine-pistol, but this was not to Thompson’s taste and it was suggested that it be called a ‘sub-calibre gun’ to show that it used a smaller cartridge than a rifle. This term was already in use, however, for military rifles that were fitted with small-bore training barrels for target use, usually of .22 calibre. It was believed that prospective purchasers would be confused by this term, so during one of Auto-Ordnance’s meetings someone (exactly who was never recorded) suggested the term ‘submachine gun’. Further suggestions about its possible name were bandied about, and it very nearly became the Ryan submachine gun, after Thomas Ryan. Ryan himself disapproved of this name, stating he knew nothing about guns, and suggested it simply be called the Thompson gun – and so it was.

  COLT AND THE NEW MODEL 1921

  Auto-Ordnance was not capable of volume production of the new weapon, having only a small machine shop with nine staff, so if the new gun were to be manufactured in quantity and at reasonable cost, it needed facilities for mass production. The simple answer was to use the huge engineering potential of the Colt Patent Firearms Company at Hartford, Connecticut, which had already been assisting with the development of the M1919. General Thompson had previously worked closely with Colt on the M1911 pistol, so it was not unsurprising that in August 1920 Auto-Ordnance signed a contract with Colt to make 15,000 guns at the rate of 100 guns per day, at an initial price of $38.25 per gun. Colt was also contracted to produce the magazines.Work began straight away on tooling up, Colt taking one M1919 gun to use as a pattern, and by February 1921 they had the machinery in place to begin manufacture. The first guns were produced by 30 March 1921 and all were checked by Auto-Ordnance’s own inspector, Major John Barrett, a very experienced man who recorded every detail of their manufacture, inspection and shipping. These Colt- Thompsons were made to very high standards of workmanship and began their lives with the nomenclature ‘Model of 1921A’ . Some 15,000 would be manufactured. The guns bore all of the hallmarks of the original Thompson design, with a 10½in (26.6cm) finned barrel and a blade fore-sight; they were also fitted with an adjustable Lyman ladder-type rear sight, which required the centrally mounted cocking handle on the top of the receiver to be slotted to enable aim to be taken through it. There were distinctive walnut fore and rear pistol grips but the most noticeable addition was that of a walnut stock, which fitted on sliding rails under the rear of the receiver and could be removed in seconds by pressing a release button. The stock provided much improved grip for shooting, made for steadier aim and helped control the recoil. There was a fire mode selector switch on the left side, providing either full-auto or single-shot modes, and a safety lever that worked by blocking the sear. The gun could use a 20-round box magazine, but the receivers were all machined to accept the 50- or 100-round drum magazine. As the gun was capable of a theoretical rate of fire of 800rpm, a 100-round drum capacity was not regarded as excessive, although it added 3lb 2oz (1.4kg) to a gun that was already tipping the scales at 10lb 4oz (4.6kg) empty. All guns were serial numbered on the left receiver, under the butt stock on the frame and under the fore-grip. In 1926, Colonel Richard W. Cutts and his son had begun work designing a ‘compensator’ that could be fitted to the barrel of a rifle or machine gun. It would allow the muzzle blast generated by the propellant gases to vent upwards, helping counteract the tendency of automatic weapons to muzzle-climb when being fired. Initially, Cutts tried attaching weights to the muzzle, a system that worked but was hardly practical. The idea for using the muzzle gas to counteract climb actually came from some old-established technology. ‘Falling back on the principles of steam engineering as applied to turbines, we discovered that we could harness the power of propellant gases and thereby reduce the recoil, by attaching an expansion chamber and tube at the end of the barrel.’ Determining the effectiveness of the designs posed something of a problem, however, so Cutts approached Philip Quayle, a physicist working at the Peters Cartridge Company of Ohio, and put the problem to him. Quayle was a gun enthusiast who had developed a high-speed camera that could film bullets in flight. ‘This allowed us to see the results of the changes we were making in the design of a compensating device.’

  Muzzle-climb certainly posed a problem for anyone using an M1921 in full-automatic mode, for unless fired in short controlled bursts the Thompson would invariably end up pointing high and right of the point of aim. Solving this challenge became Cutts’ personal obsession, as
he explained:

  As the gun recoiled after the first shot and before the shooter could recover from the kick, the gun would fire its second shot and the muzzle would bounce still higher. Successive shots would punch the muzzle up and up, with the shooter himself actually hindering it, because his muscular effort and delayed muscular reaction prevented the gun from dropping to its original level so that its jump started from a higher point after each shot.

  The net result was a simple screw-on compensator with four vertical vent slots that allowed the gas to blow upwards on firing; this system created a powerful down-thrust that helped counteract the muzzle-climb. The Lyman Corporation liked the idea and offered to manufacture the Cutts compensator on the basis of a $1 commission to Colonel Cutts per unit sold. They began to appear on Thompsons from early 1927 onwards and guns supplied with them were advertised as M1921ACs. Further development of the Thompson did not stop with the introduction of the M1921, for a number were converted at the factory to semi-automatic fire only. The rationale behind this conversion is not easy to determine, but it is probable that there was some demand for a cheaper version that was more controllable than the full-auto version. How many were made is not known, possibly fewer than a hundred and original examples today are rare.

  1. A view of the Model 1921AC, showing its very distinctive silhouette. Many collectors and firearms historians believe this to be the most classic of all the Thompson models.

  2. The beautifully sculpted foregrip, with front mounted sling swivel. 3. The quick-release stock showing the machined slot into which the guide rails on the receiver slotted.

  4. The patent markings on the left side of the receiver. 5. Colt’s markings on the right.

  6. The Lyman rear sight, graduated to 600 yards. Note also the Auto-Ordnance ‘bullet’ logo on the receiver. 7. The effective Cutts compensator. It is attached by means of a pin visible below the fore sight to the right of the picture.

  8. The breech-block and firing-pin aperture. The body was slotted to enable the Blish lock to fit inside it. 9. The Blish lock, showing its very complex shape. Machining this was both time consuming and costly and omitting it from the later guns made for considerable savings without impairing performance. 10. The actuator, or cocking handle. Later models had a heavier actuator fixed to the right side of the breech-block.

  THE BRITISH THOMPSONS

  In May 1921, General Thompson went on a sales tour of Europe, visiting Belgium, Britain, France and Spain. He was invited to demonstrate the M1921 at the Royal Small Arms Factory at Enfield on 30 June 1921, which he did with some success. The resultant report made by the Chief Inspector of Small Arms makes interesting reading. Although it is too long to reproduce in full, some sections concerning the accuracy and reliability of the gun are worth reproducing. There was some puzzlement expressed about the requirement for the Blish locking system, albeit couched in faintly impenetrable army technical language.

  There is an element of doubt as to whether the use of the lock is a positive one. The inclination of the sides of the ‘H’ and the corresponding angle of the grooves in the breech block tend to closure, whereas … the inclination of the outside ‘ears’ and the corresponding angle of the grooves in the receiver tend to release. It is well known that with pistol ammunition the inertia weight of the breech block and the resistance of its return spring afford sufficient resistance to hold up the cartridge [case] while the bullet leaves the barrel, provided such weight and spring resistance are correctly worked out. 2

  In simple terms, the Chief Inspector was questioning the necessity of the Blish lock, as the counterbalancing weight of the breech-block and its recoil spring, matched to the cartridge performance, should in theory provide sufficient delay on opening when operating on a straightforward blowback principle. Indeed, the Small Arms staff at Enfield pre-empted the alteration of the design of later Thompsons by removing the Blish lock completely and then firing the gun remotely under safe conditions. The results were instructive: ‘The rounds were fired, both ejection and extraction being satisfactory. The gun functioned well and the condition of the spent cases was found to be identical with that of the spent cases … fired with the wedge assembled to the gun.’ There was also doubt about the efficacy of the drum magazines: ‘The 20 round box magazines are much simpler than the drum magazines and appreciably lighter for the same number of rounds, 5 empty box magazines holding 100 rounds in all weighing 2lb as against 3lbs 2ozs for the 100 round drum and 2lbs 8ozs for the 50 round drum. The box magazines are simpler for packing and transport.’ There were a few reliability problems when the Thompson was tested, mostly with ammunition failing to fire (not necessarily the Thompson’s fault), and some ejection problems. But overall the British report praised the Thompson: ‘The weapon is handy, compact and is designed in a manner convenient for manufacture.’

  George Goll firing an M1921 Thompson in front of an invited audience of British officers at Bisley Camp in summer 1921. The climbing muzzle caused by the recoil on the gun can clearly be seen and Lyman sights would have been of questionable practical use.

  Left is a .30in Springfield round which proved too powerful for the initial Thompson design. Next are the .45in Colt ACP and 9mm Luger Parabellum cartridges, both of which were used in Thompsons, and lastly a .32in Colt automatic cartridge for comparison.

  But there were no orders forthcoming, the British government being very reluctant to spend money re-equipping the army with a weapon that was relatively expensive, unproven in combat and went against all of their guiding principles with regard to issuing automatic weapons to soldiers. This was, after all, the same army command that had insisted that the Lee-Enfield rifle be fitted with a magazine cut-off ‘to prevent the unnecessary expenditure of ammunition’, and which refused to countenance the issue of semi-automatic pistols to their soldiers during the Great War for similar reasons. The prospect of actually giving the soldiery a gun capable of such high rates of fire horrified many at the Board of Ordnance, and in the wake of the public’s distaste for anything involving military expenditure after 1918, there was little chance of the Thompson being adopted by Britain.

  A military Model 1923 Thompson with fitted bipod and 16in barrel. The Thompson could not cope well in a sustained fire role due to overheating.

  Undeterred, the designers continued to try to find a way to get their gun purchased in Europe. Demonstrations to the French Army in 1921 and 1923 were moderately successful, but the testing was marred by component failure: ‘It was observed that the bolt had broken in two parts. This must have occurred before the shooting [test] was over because the break had very pronounced caulking.’ Unmentioned at the time was the fact that despite this damage, the Thompson had continued to function, whereas most other submachine guns would have ground to a halt. The Belgian Army were quite impressed with the Thompson, when it was demonstrated to them in 1923, but they wanted it chambered for the 9mm Parabellum cartridge, then an extremely popular calibre in Europe.The dilemma faced by Auto-Ordnance was that they could not easily set up manufacturing facilities to make variants of the gun, so they approached the Birmingham Small Arms (BSA) factory in 1925 with an offer that BSA make, under licence, ‘European’ models of the Thompson. Little of the history of these guns has survived, and they are not generally well known outside of collectors’ circles, but the first of the preproduction models was named ‘Model of 1926’ and was chambered for 9mm. It had been designed by BSA’s brilliant engineer George Norman and bore only a passing resemblance to the original Thompson guns. It had a wooden stock and fore-end that enclosed the front of the receiver, an unprotected 300m (328-yard) graduated ladder-type rear sight, a deeper, milled receiver with separate selector and safety levers, and a magazine release catch that was considerably simplified compared to the M1921.

  In January 1927, the first 9mm example was demonstrated to the French military weapons testing facility at Versailles (the VTC). The gun was also supplied with a bipod to permit sustained fire, as crucially it
s rate of discharge had increased from 800rpm to a blistering 1,200rpm. Yet inexplicably, no drum magazines were available, and it was only tested with the 20-round box magazine. Extracts from the subsequent French report are instructive:

  The Thompson submachine gun discharges in single fire or as a machine gun. In the first case, precision [accuracy] is excellent up to 600 metres; in the second the overly rapid rate does not allow the weapon to be shot unsupported without excessive scattering [of the bullets]. The weapon underwent a test fire of 3,500 rounds with 2,500 in automatic fire, which led to only a few minor problems, but inspection … revealed a broken bolt and galling on the Blish lock, on the cocking notch and on the tip of the sear.

  Clearly, the French were not overly impressed with the performance of the weapon, as in single-shot mode it was not as accurate as a rifle, and in full-auto mode it was difficult to control. They concluded: ‘Following an earlier weapon study of this type, the VTC were not interested in guns shooting ordinary pistol cartridges. The latter [test] shows, compared to the same type of weapons studied in France, no marked improvement.’

  Despite the production of the 9mm gun, neither the French nor Belgian Army placed any orders. This lack of response, however, did not stop BSA from working on an improved model, the M1929, which bore a stronger resemblance to the original M1921 design, with a plain wood fore-end and a bird’s head pistol grip on the stock to provide a surer grip. This stock mutated into a more elegant sporting type, with a swell for the trigger hand to aid grip. The magazine was curved and a number of different calibres were offered, including 9mm Bergmann and 7.63mm Mauser, but despite the improvements no major orders were forthcoming, and BSA ceased production of the Thompson in 1930.