National Army Museum lecture - The development of British Light Automatics

(Thus is the original script for  lecture I delivered at the National Army Museum in July 2022, as part of their "spotlight saturday" event commemorating the Machine Gun Corps.  The final lecture differed slightly, as the sections on the LSW and Minimi were ultimately removed to keep within the timeslot.

The actual talk is available here - https://www.youtube.com/watch?v=2IRm1XD8je8)

Introduction

The British Army started the Great War with a section of two Vickers guns attached to each infantry battalion, though some were still equipped with the older and heavier Maxim.

While the water cooled Vickers was probably the best gun in its class, and capable of prolonged sustained fire, it did have some problems.

Firstly, it was a water cooled, tripod mount weapon, and not really suitable for firing on the move to support advancing infantry.

Second, it was a complex and precisely machined weapon, and additional guns could not be produced fast enough to equip the rapidly expanding army. While Vickers production would rapidly ramp up, it would create a "machine gun gap" for the early years of the war.

These two factors created an opening for a new category of weapon - what would become known as a "Light Automatic" - with consequent change on tactics and unit organisation.

The Lewis Gun

The Lewis Gun was designed by an American, Col Isaac Newton Lewis. It was based on an earlier weapon, the unsuccessful water cooled McLean gun, but Lewis significantly improved the design and modified it into an air cooled weapon.

At least some of the changes were simply to avoid Maxim's patents, which were extensive and Lewis therefore had to find different ways to do almost everything, including the basic action, cooling and feeding the gun.

Lewis initially tried to sell his gun to the US Army, but there was some personal animosity between Lewis and General William Crozier, head of the Ordnance Department. who Lewis has criticised previously. In addition, the US had already purchased the Benet-Mercie light machine gun. This was supposedly designed by the son of a previous head of the Ordnance Department, but was actually just a variant of the light Hotchkiss.

The upshot was that the US Army was not interested, and Lewis took his design to Europe, where he had 50 guns handmade by BSA in 1913, chambered seven difference calibres to use as sales demonstrators.

With the outbreak of war in 1914, the British government bought all the available prototypes and placed an order for 1,000 guns in 1914, followed by another order for 3,000 more the following year.

The army's initial impression of the Lewis was not favourable. The only machine guns they had experience and doctrine for was the much heavier Vickers, and they initially tried to use the Lewis in the same way, mounted on the same tripod.

As you would expect, the lighter Lewis was not capable of providing the same sort of sustained fire, and it was some time before the army worked out the best way to use it as a more mobile weapon - what came to be termed a "light automatic" rather than a machine gun.

The Lewis Gun - Technical

The Vickers gun was operated by recoil, which is very robust but requires a solidly constructed - and therefore heavy - weapon. By contrast, the Lewis is gas operated. Some of the propellant gas is tapped off near the muzzle into a gas cylinder, where it drives a piston backwards to work the action and compress the mainspring for the next shot

The mainspring is a coiled clock type spring rather than the straight type used on later weapons, housed in a hump just ahead of the trigger. As well as being complex, this put the spring close to the breach, where it heated up and gradually lost its temper as the gun fired, eventually causing a stoppage.

The Lewis is an air cooled gun - when it is fired, it creates a temporary vacuum inside the muzzle end of the cooling jacket, and this pulls air into the rear of the jacket and over the aluminium cooling fins surrounding the barrel, which give maximum area to radiate heat away.

The fins are made of aluminium partly to reduce weight, but also because aluminium has six times the heat conductivity of steel, The shroud surrounding the barrel gets notably hot - after a couple of hundred rounds, it is too hot to hold, and we meet accounts of men using sacking or their tunics to hold a hot gun when they couldn't fire it from the bipod. After the war, a stirrup grip was added, but this is a post war feature.

Overall. this was much lighter than the water cooling system, but it also couldn't deal with prolonged sustained fire.

Despite the forced air cooling, the gun will overheat and simply stop firing due to heat expansion of components. The 1918 manual says this typically happens after 800-1,000 rounds of rapid fire, though individual guns vary, and after that it will need half an hour to cool.

The Lewis fires from an open bolt, so the bolt is held to the rear when it isn't firing. When the trigger is pulled, the bolt goes forward, strips a cartridge off the magazine, pushes it into the chamber and immediately fires it. This is less accurate than the equivalent closed bolt system, where the bolt is forward with a cartridge in the chamber when not firing - pulling the trigger then fires the cartridge immediately, before the bolt back and pick up another cartridge ready for the next slot.

However, an open bolt gun allows the chamber to cool off better between shots, and avoids the risk of cartridges "cooking off" as they sit in a hot chamber.

The Lewis doesn't have a single shot setting, though an experienced shot could squeeze off a single round by careful trigger control; betting on their ability to do so seems to be a common way for instructors to win beer money off their trainees.

The Lewis is fed from a 47 rd pan magazine on top of the gun. It isn't actually a drum - it is open bottomed, and there is no magazine spring, as the feed is actually powered mechanically from the gun.

It was this pan magazine, as well as the weight, this made the Lewis much easier to fire on the move than the Vickers - as the latter uses a non-disintegrating fabric belt, you not only have the full belt feeding into one side of the gun, you have expended canvas belt trailing from the other to tangle round your legs.

However, the weapon's mechanism does rotate the drum as it fires, so the gunner had to hold the gun away from his body and canted to the right if firing from the hip, or the pan will snag on your uniform or equipment and cause a stoppage.

There is a 97rd aero drum, but it isn't compatible with ground guns - the magazine peg is too short for the catch to lock the taller pan in place, and it blocks the infantry sights.

The Lewis Gun - Tactical

Having looked at the gun from a technical viewpoint, it is time to look at it - and the men who carried it - from a tactical viewpoint.

Each infantry battalion began the war with a section of two Vickers machine guns, increased to four guns in February 1915. From October 1915, however, the Vickers guns were stripped out of the infantry battalions and centralised as Brigade machine gun companies of the Machine Gun Corps.

Each infantry battalion received four Lewis guns in return, an exchange many were unhappy with, since the Lewis was initially regarded merely as an inferior version of the Vickers, rather than a new kind of weapon.

Lewis gun allocations increased as more became available, though the initial priority was to provide guns for new units as the army expanded, rather than to increase the number held by existing units.

By the battle of the Somme in mid-1916, each infantry battalion should have had 16 Lewis guns, or one per platoon, though some had yet to receive their full allocation.

By late 1918, supply of Lewis guns had increased until each infantry battalion was provided with 36 guns, two per platoon plus four additional guns held by the battalion HQ for anti-aircraft use.

A Lewis gun section was supposed to have eight men plus a Corporal in charge, but casualties and manpower shortages meant they were usually understrength. Harry Patch, who was a Lewis gunner, recalls the Lewis section he joined as having five men including himself.

The No 1 is also usually the section commander. He carries the Lewis gun (unlike the Vickers section, where the No 1 carried the tripod, as siting the gun was considered so important) and fires it in action. He has a revolver as well as the Lewis.

The No 2 is the assistant gunner. He carries the spare parts bag, which is very comprehensive and weighs 15 lb - these are specialist weapons, compared to the section LMG of later years. He carries a revolver rather than a rifle, and in action he changed the ammunition pan and helped the gunner deal with any stoppages.

Nos 3, 4 and 5 were ammunition carriers. Each of them carried a rifle, though their primary purpose was to carry Lewis ammunition.

The 1908 pattern webbing was designed around clips of rifle ammunition and made no provision for carrying Lewis magazines, and it was awkward to carry many in a knapsack, so from 1917 the ammunition carriers were issued a set of four circular webbing magazine pouches, linked by straps which went over the wearer's normal webbing like a waistcoat. Two of the pouches sat against the wearer's back, below the pack, and two on the front. Each pouch could hold two Lewis magazines, though it was common to load only one magazine in each if the wearer had to cover difficult terrain.

Finally, the section would also have 2-3 riflemen to act as local protection and scouts. They might carry a few drums of ammunition, but they were intended to be more lightly loaded to preserve their mobility.

It is important to remember that each 1916 platoon contained three rifle sections supported by a dedicated Lewis section; the concept of each rifle section having its own LMG didn't happen until WW2. The Lewis was still a specialised weapon, rather than something every infantryman would be trained to use.

In theory, all members of the section should be trained Lewis gunners, but often in practice only the number 1 and 2 were actually qualified. Lewis gunners were selected on the basis of accuracy, and were supposed to be marksmen, getting another 6d a day on their pay.

Numbers of marksmen graduating from basic training dropped as training became steadily more abbreviated as the war ground on - by 1917, almost everyone completing basic as a marksman was assigned either as a sniper or a Lewis gunner.

Lewis gunners were issued sleeve qualification badges - initially the same “MG” badges as Vickers gunners, then from 1917 a separate "LG" badge. It often wasn't wise to wear these in action - like snipers and flamethrower operators, captured machine gunners were sometimes shot out of hand.

The Lewis was produced in Britain by BSA, and .303 guns were produced by Savage Arms for the Canadian Army. Savage also produced Lewis Guns in the American 30-06 calibre for US forces.

Overall, around 145,000 Lewis guns were produced for Commonwealth forces during the war, compared to just under 74,000 Vickers guns, making it by far the most numerous machine gun in British service.

Aerial Lewis Guns

A prototype Lewis Gun became the first machine gun fired from an aircraft in 1912, admittedly largely as a publicity stunt,

The Lewis had several advantages as an aerial gun. The first and most obvious was its light weight, but the mechanical feed from its pan magazine would also work at any angle, which the belt feed on guns such as the Vickers would not.

On the other hand, its open bolt operation was too inconsistent to be synchronised with the propeller, and it could only be mounted in installations outside the propeller arc.

This wasn't a problem for flexible-mounted defensive guns used by observers. However, it meant that Lewis gun mounts for single seat fighters were normally mounted above the wing and fired via a Bowden cable, with the gun pulled back and down a sliding track for reloading.

Many of the early guns were simply ground guns with part of the cooling sleeve cut away. Later aerial guns were built without any cooling sleeves, as they were never likely to fire the number of rounds required to overheat.

They were also modified to take larger 97 round pans to avoid the need for reloading, and fitted with special sights. In practice, however, many pilots simply aimed using tracer. Butts were replaced with spade grips, and bags added to catch spent cases before they could cause damage to engine or control surfaces.

A significant proportion of early production went as aerial guns - in the case of the US, for example, this consumed essentially the whole of Great War production, and none were available as ground guns so US troops had to use the dire French Chauchat CSRG instead.

They were replaced in the 1930s by belt fed guns in the wings, or by flexible guns with a higher rate of fire such as the Vickers K.

A large number of surplus aerial guns were refitted for ground use after the huge equipment losses at Dunkirk and issued to the Home Guard, including 60,000 British guns and another 40,000 bought from the US.

Lewis Gun users

Aside from British and Commonwealth forces, Lewis guns were produced by Savage Arms in the US 30-06 calibre for use by American forces, though few were available as ground guns until after the war.

The Germans were very impressed by what they called the "Belgian Rattlesnake", and converted more than 10,000 captured Lewis guns to their own 7.92mm Mauser ammunition for issue to their own troops. Indeed, the standard German Machine gunner's course covers the Lewis as well as the MG08 in detail.

Finally, both the Dutch and the Japanese bought the Lewis in the 1920s, and continued to use them on into WW2

The Hotchkiss Light Machine Gun

Along with the Lewis, the British Army purchased another light machine gun during the Great War, as it struggled to obtain sufficient light machine guns.

The light Hotchkiss or Hotchkiss portative was a much lighter version of the heavy tripod mounted Hotchkiss used by the French.

It was essentially the same weapon as the Benet-Mercie adopted by the US, but while that acquired a very poor reputation in US service, this seems to have been a problem of crew training, and the British did not experience the same problems with it.

It was a gas operated weapon fired from a bipod, and fed from rigid 30rd strips. It relied on simple air cooling, but as it lacked the forced air cooling sleeve of the Lewis it would overheat faster.

It was only purchased in small numbers, and went to either the light machine gun sections of cavalry regiments or as machine-gun armament to some marks of tanks.

The Bren Gun

The Lewis was probably the best of the Great War light machine guns, but it was far from perfect. In particular, the army wanted something lighter and less complex.

In 1922 the Small Arms Committee recommended a version of the US-made Browning Automatic Rifle chambered for the British .303 round, which was indeed lighter and simpler, though its fixed uncooled barrel and bottom mounted 20 rd magazine would have meant a significant reduction in sustained fire capability.

However, with spending cuts and a large stock of adequate if ageing wartime Lewis guns in stock, little was done in the 1920s until those weapons began to wear out.

In 1930, the Small Arms Committee began the search for a weapon to replace both the Lewis and the sustained fire Vickers, which was obviously a tall order.

A number of guns were tested, including the Vickers-Berthier that we will look at later, but a clear favourite quickly emerged in the form of the Czech Zb 26, originally chambered for the very common German 7.92mm Mauser cartridge. An improved Zb 30 was re-chambered for the British .303 and a modified version was adopted in 1935.

A production line was set up at Enfield, with the first gun completed in September 1937. 30,000 or so of these "Mk 1" guns had been produced by the start of WW2, but almost all were lost with the BEF in France in 1940.

To replace these lost guns, and to support the expansion of the army, the Bren was simplified to facilitate mass production. The Mk 1 (Modified) simply omitted some of the inessential features such as machining away surplus metal to reduce weight.

The Mk II was redesigned from the ground up for ease of manufacture and entered production in 1941. It replaced the complicated drum rear sight of the Mk I with a simpler ladder sight, replaced the original folding cocking handle with a simpler fixed design and had a simpler bipod and butt plate without shoulder strap or rear handle. Finally, the gas cylinder and barrel was re-designed so only the critical gas block had to be machined from hard-to-work stainless steel. Overall, these changes increased production by around 20-25%.

The Mark I (modified) and Mk II made up the great majority of the 500,000-odd Brens produced.

However, there were trials in 1943 to produce a lightened Bren for paratroopers and jungle warfare.

This produced the Mk III in July 1944. It was essentially a lightened version of the Mk I (modified) but fitted with the simpler ladder back sight and a lighter, shorter barrel. About 50,000 were produced. The Mk IV was functionally identical but based on the Mk II gun, and very few were actually made.

The Bren - Technical

Like the Lewis, the Ben was a gas operated weapon. However, the complex clock-type mainspring of the Lewis was replaced by a simpler straight coil spring in the butt, where it was no longer heated by the barrel so that it lost its tempering and caused stoppages.

The Lewis used air cooling, which limited its sustained fire capability, while the Vickers used water cooling, which was heavy. The Bren sidestepped the problem by using a quick-change barrel.

After 300rds at the "rapid rate" of 120 rounds per minute, the barrel started to overheat. At this point, the No 2 changed the barrel by unlocking the barrel catch and using the built-in carrying handle to rotate the hot barrel and lift it off the gun. The first barrel was then put aside to cool, while the No 2 locked the spare barrel in place, and the gun continued firing. A well trained crew could change barrels in 6-8 seconds.

This gives it a massive advantage over fixed barrel weapons like the US BAR, and the carrying handle made it a much easier operation than the German MG34 or MG42, where the crew had to handle the hot barrel using asbestos pads. Indeed, it was so well engineered that it carried forward almost unchanged to its replacement, the GPMG.

The Bren fed from a 30 rd box magazine mounted on top of the gun. The made for quick and easy magazine changes by the No 2, but meant that the sights had to be offset to the left side of the weapon.

The box magazine protected the rounds much better than ammunition belts or the open pan magazine of the Lewis. It also meant you could pick up and fire the gun from the hip or on the move without worrying about trailing belts, making it a better assault weapon.

There was a 100rd anti-aircraft drum. It blocked the regular sight, and could only be used with special AA sights, and so was rarely seen except on tanks where four drums were part of the vehicle stowage.

The Bren safety catch had three positions - Safe, “Rounds" or semi-automatic and fully automatic. fire. The single shot setting was used to allow the Bren to fire without giving away the presence of a machine-gun until the enemy were within good killing range. However, it was normally fired in 4-5 round bursts; shorter bursts made it difficult to observe the impact of rounds, while longer bursts wasted ammunition and overheated the barrel too quickly.

Overall, the Bren was much simpler and more dependable than the Lewis - the list of potential stoppages in the manual included only 8 items, of which the first and most common was “Empty magazine”.

It was notably accurate - indeed, some felt it was a little too accurate for suppressive fire - and its quick-change barrel gave a far greater sustained fire capability than the Lewis, though it was never able to replace the Vickers in the sustained fire role; Britain wouldn't move to a universal machine gun until the Bren's successor, the GPMG.

The Bren was used by all Commonwealth forces, including the Canadians, Australians and Indian Army, and significant numbers were supplied to allies and resistance groups.

The Bren was originally manufactured at Enfield, and it remained the largest producer, making just under 280,000 Brens.

However, work began in 1938 to produce Mk I Brens at the John Inglis plant in Canada. The first Inglis Brens appeared in 1940, and the plant produced 186,000 guns during the war. A modified version of the Mk I Bren was also produced at the Lithgow Factory in Australia in 1940, but produced only 17,000 guns.

Finally, the Ishapore Arsenal in India switched from producing the Vickers-Berthier to Brens in 1942, and production there for the new Indian Army continued well the war.

The Bren - Tactical

The adoption of the Bren led to a reorganisation of the infantry platoon. It had previously been made up of three rifle sections plus a Lewis section to provide fire support. Now, each platoon was made up of three identical sections, each with both riflemen and a Bren LMG and capable of performing any tactical role.

Each ten man section divided into two elements, and these normally alternated providing fire and movement.

The first element was a rifle group lead by the section commander, usually a corporal armed with a Sten SMG, and six riflemen with Lee-Enfields. Each rifleman carried two Bren magazines in addition to ammunition for his own weapon; the universal ammunition pouches of the new 37 pattern webbing were specifically designed to hold Bren magazines in addition to rifle clips and grenades.

The second element was the Bren group, lead by the section lance-corporal armed with a Lee-Enfield, plus the Bren No 1 with his Bren gun and a No 2 with a Lee-Enfield. All three members of this group carried four Bren magazines each, and the No 2 also carried the spare barrel and tool wallet.

Overall, this gave each section 25 loaded Bren magazines - 750 rds - plus another 250 rds on the platoon truck.

The Bren was mostly used from its bipod, but each infantry platoon was issued with a tripod, which could be used to set up one of the guns up for sustained fire on fixed lines, or for anti-aircraft work.

Unlike the Lewis, the Bren was simple enough that every infantryman was expected to master it, rather than just specialists.

The 7.62mm NATO Bren

When Britain converted from the .303 round to the new NATO standard 7.62mm round at the end of the 1950s, it adopted the FN MAG as the General Purpose Machine Gun or GPMG. As the name suggests, this was finally able to replace both the Bren and the Vickers, and was also used as a vehicle gun.

The GPMG was an excellent weapon, effectively combining the easy quick-change barrel pioneered on the Bren with a belt feed for more firepower. In the infantry platoon, it was a straight replacement for the Bren, and each section kept the rifle group and gun group organisation that persisted until the switch to the SA80 in the 1980s.

Despite this, some Brens were converted to 7.62 NATO, and remained in limited service for another twenty years. As the 7.62mm round was almost identical in muzzle calibre to the old .303 and had a slightly shorter cartridge case, the conversion was fairly straightforward.

The converted guns could feed either from a new 30 rd magazine – notably straighter than the old curved magazine as the new round was rimless – or from standard 20rd SLR magazines.

Early 7.62 Brens were issued with two steel barrels like their .303 counterparts, but from the L4A4 in 1961 they were issued with a single chromed barrel instead. Although more expensive, these had a much longer barrel life and took longer to overheat so a spare barrel was no longer necessary.

The re-barreled Brens were typically used where feed belts might tangle or pick up contamination, such as in jungle operations. The Royal Marines were notable users, as they regularly deployed to Norway where box magazines had an advantage over ammunition belts, which could clog with snow and freeze solid.

The marines took these guns to the Falklands as a second automatic weapon in the section to give additional firepower. As the rest of the section were already carrying extra linked ammunition for the GPMG, they usually couldn’t carry further extra ammunition for the L4A4 as well, and they were used more as heavy automatic rifles than machine guns.

The Vickers-Berthier

The Vickers-Berthier was originally a French design, but the licence to produce it was acquired by Vickers in 1925 to complement their heavier water cooled guns, and in the hope of selling it to the Army as a replacement for the Lewis.

It was entered in the 1932 trials for a Lewis replacement, and though the British Army didn’t buy it, preferring the Bren, the Indian Army did adopt it in 1933, primarily because it would be available much earlier without the need to convert an existing design to .303 as would be required for the Czech ZB design.

The Indian Army set up a production line at the Ishapore Arsenal, with the first guns being produced in 1933 – four years earlier than the first Brens, and probably much longer before they would have been available to the lower priority Indian Army.

The Vickers-Berthier was technically similar to the Bren, and indeed it is often mistaken for it. The Vickers-Berthier saw service with Indian Army units in the Far East and North Africa, and performed acceptably enough. It was replaced by the Bren as the latter became available in numbers, and the Ishapore factory converted from producing Vickers-Berthiers to Brens in 1942.

The SA80 onward

From the 1960s to the 1980s, British rifle platoons had a 7.62mm General Purpose Machine Gun in each section. This was an excellent belt fed weapon with a quick change barrel.

However, when Britain adopted the 5.56mm L85 to replace the ageing SLR in 1986, it also adopted the L86 Light Support Weapon to keep ammunition compatible within the rifle section.

The LSW was essentially a version of the rifle with a longer barrel and bipod. The original prototype included features which would have made it better for sustained fire, such as a quick change barrel and firing from a closed bolt on semi-auto for accuracy like the rifle but from an open bolt on automatic operation to prevent overheating. However, these features were dropped from the final designs to increase commonality with the rifle and keep costs down.

It was a bullpup design, which reduced the overall length and used the same 30 rd box magazine as the rifle. It was always designed as a one man gun, with the eight man section breaking down into two four-man “bricks” each with three riflemen and an LSW gunner.

Each platoon would retain a single GPMG in platoon HQ, set up with a tripod for the sustained fire role.

The LSW’s good point was its accuracy, especially since it was fitted with the SUSAT optical sight, at a time when most other countries weren’t fitting light weapons with such devices as standard.

Like the rest of the SA80 family, it initially had significant issues around reliability and durability. These were eventually fixed by the significant upgrade to the A2 version by Heckler & Koch in 2002, but that was more than a decade after initial issue.

Even so, it had very limited sustained fire capability, and its smaller 5.56mm round lacked the range and penetration of the older 7.62mm round.

As a result, the LSW was “supplemented” – the Army was very careful not to say “replaced” - by urgent purchases of the FN Minimi for the first deployments into Afghanistan and Iraq.

These were designated as the L108 or L110 in British service, depending on whether you have the para version with a shortened barrel or not.

The Minimi was a belt fed 5.56mm machine gun with a quick change barrel and firing from an open bolt. This gave it the sustained fire capability that the LSW lacked, though it was inevitably constrained by its smaller cartridge.

This was particularly notable in Afghanistan, where longer ranges saw the GPMG return to regular usage as a section weapon, despite its weight.

The LSW did enjoy a brief use as a “dedicated marksman” rifle for longer range work, but was replaced by the 7.62mm semi-automatic L129A1 Sharpshooter Rifle.