British Enfield SA80 Part 1: Mock-ups

Note: The information in this article has been superseded by that published in Jonathan Ferguson’s important original research work, Thorneycroft to SA80: British Bullpup Firearms, 1901–2020. That book is available from the Headstamp Publishing website:

This post accompanies the fourth in a series of collaborative videos produced with ARES Researcher Ian McCollum, who also runs the Forgotten Weapons blog and YouTube channel. Using access to unique collections facilitated by ARES, this series of videos will examine a range of interesting weapons over the coming months. Each video will be accompanied by a blog post, here on The Hoplite, and supported by high quality reference photographs. – Ed.

Jonathan Ferguson

First Steps

In 1951, the United Kingdom chose to abandon the advanced E.M. 2 (today generally rendered ‘EM-2) self-loading rifle chambered for the intermediate 7 mm (.280 British) calibre, which had been briefly adopted as ‘Rifle, No.9’, and instead sought the promise of NATO standardisation in the Belgian FN Herstal FAL and the 7.62 x 51 mm cartridge. This resulted in adoption of the semi-automatic only L1A1 Self-Loading Rifle (SLR) in 1957. Subsequently, drawing upon practical experience in Vietnam, the US went its own way and adopted the ArmaLite AR-15, chambered for the small-calibre, high velocity (SCHV) 5.56 x 45 mm cartridge. The AR-15 was initially adopted as a substitute service rifle (as, indeed, it was adopted by the British in 1963) and latterly as the standard issue self-loading service rifle. With the SLR already becoming costly and difficult to maintain by 1970, the British Ministry of Defence initiated a new effort to find its eventual replacement, envisaged as replacing the SLR from 1980 onwards. The 7.62 mm SLR was seen as too heavy and too long for contemporary mechanised warfare, and too hard-recoiling to train troops to shoot well. In common with many ‘Western’ nations, Britain sought a new, lighter infantry weapon with reduced weight and size, still providing adequate lethality but increased hit probability. The AR-15 was to serve as a benchmark, but no serious thought went toward off-the-shelf procurement or licenced manufacture. There seems to have been a strong desire to design and build something in Britain, at a time when the UK still had the industrial capacity to do so. Cost was an issue, so a pressed steel and polymer construction was assumed from the outset.

Wooden Mock-Ups

Today, firearms designers will use digital 3D modelling and, increasingly, additive manufacturing (3D printing) to design and test the general arrangement and ergonomics of a proposed weapon or accessory in three dimensions. This allows for an initial assessment the ease of operation, approximate weight, balance, ‘handiness’, and other characteristics, and influences the finer points of design. Traditionally, gunmakers would craft a wooden mock-up to achieve the same thing. This artefact of the SA80 programme is just such a mock-up, and it is a wonderful (if not especially decorative) piece of craftsmanship. It is composed mainly of black-painted wood, with some metal components: the barrel, flash suppressor, sling loops, trigger guard, handguard retaining band, faux bolt and return spring, a complete EM-2 optical sight, and two metal reinforcing plates for the magazine well and bolt handle cut-out respectively, as well as various pins and screws. There are only two genuine firearm components on the ‘gun’. One is the rubber eyepiece from a Sight Unit, Infantry, Trilux (SUIT) optical sight, as then used on the SLR when issued on designated marksman basis. The fake sight on the mock-up is intended to be the ‘streamlined’ prototype then under development and by then already known as the ‘Sight Unit, Small Arms, Trilux’ (SUSAT; the SUSAT remains in limited use today). The other, intriguingly, is the butt-plate. This is marked ‘D.R. Co.’, indicating a subcontractor to Enfield, and ‘C.R.1194’, referring to a drawing number. As shooters of ‘miniature’ rifles will know, this is the butt-plate from a Rifle, No.8; the standard Enfield bolt-action .22 LR military training rifle still in use by cadets today.
The mock-up features some moving parts, namely a detachable magazine, sprung moving trigger, functioning safety, a detachable mock SUSAT sight, and unlike any later version of the design, a 1x optical sight (an actual EM-2 ‘Unit, Optic, Sight’; UOS) built into a pivoting carry handle. This is intended to lie flat alongside the receiver when not in use, but can then be rotated into position when the SUSAT sight is removed (see below). Interestingly, the requirement for an optical sight was included at this stage due to the belief that iron sights would present too short a sight radius to be effective on a bullpup, rather than for any potential increase to user accuracy. The only markings on the piece are the numerals ‘2105’ in white paint on both sides, and ‘(721)’ over ‘120’, in black, on the right side magazine well. The significance of these is unknown.

This dummy gun was handmade to represent a design known as ‘Proposed Rifle Solution, (Patt B)’, and formed part of the ‘Preliminary Study on Small Arms System for 1980’, commissioned in September 1970. Published in December 1971, this was informed by existing designs, contemporary developments, and a set of requirements drawn up by Finabel, a pan-European organisation intended to facilitate interoperability of military hardware. The study recognised that advanced technologies such as caseless ammunition and the use of fléchettes would not be sufficiently mature in time, and instead focused on refining proven technology to fill the gap until the new millennium. The mock-ups made for this study comprised the following:

  1. Orthodox Rifle Type A – ‘straight line conventional configuration’ (similar to an AR-18)
  2. Orthodox LMG Pattern A – ‘straight line conventional configuration’ (as above)
  3. Rifle (Pattern B) – ‘straight line unorthodox configuration’ (i.e. a bullpup)
  4. Rifle (Pattern C) – ‘drop butt unorthodox configuration with area target capability’
  5. LMG (Pattern B) – ‘drop butt unorthodox configuration’

The study also produced more detailed designs on paper at 1:1 scale, although only for the three bullpup designs. These show the specifics of gas systems, working parts, buffers, and trigger mechanisms. How the bolt carrier was expected to function on a dog-legged incline is unclear from the drawings of the ‘drop butt’ weapon. A representation of a cartridge was used in the drawings, despite the lack of a decision on a calibre or cartridge type. The study advised a cartridge of between 5 and 5.25 mm in calibre for both rifle and LMG; 4.85 mm would soon be chosen as the weapon’s calibre. However, it was soon acknowledged that any new British SCHV cartridge must, by necessity, be a derivative of 5.56 x 45 mm and could not be wholly original. It is surprising that those involved thought it possible that a slightly necked-down variant of an established cartridge type might prove superior in NATO’s decisive ammunition trials only a few years away. A three-round burst mechanism was recommended for inclusion, although there is no evidence of this in the mock-up or arrangement drawing.

The report also covered ‘area effect’ weapons in some detail, and concluded that the capability to launch rifle grenades with their perceived greater lethality and area effect was probably still preferable to ‘tube-launched’ systems firing smaller munitions (i.e. under-barrel grenade launchers). To this end, a mock wooden rifle grenade was made to attach to Pattern B. Nonetheless, the ‘drop butt’ rifle did feature an elaborate under-barrel grenade launcher mock-up complete with side-opening barrel repurposed from a flare launcher. The AR-18 heritage of the Pattern B rifle is plain in its gas system and working parts. The AR-18 gas system, in particular, was recommended in the study as a sound basis for that aspect of the weapon. However, very little else was carried over from the AR-18. The trigger mechanism was at this stage based upon that of the FAL, with additions for a trigger bar. The overall height of this mechanism is the reason for the ‘bellied’ shape of the lower receiver behind the magazine well. The AR-18 magazine and magazine well are not in evidence, nor would they ever be. On this mock-up the release catch is built into the back of the magazine itself, an unusual approach not carried forward. The combined selector and safety of the AR series were also ignored. Instead, a thumb lever safety is provided which simply rotates a projection into place behind the trigger to prevent it being pulled. Oddly, given the amount of detail present in the drawing, no selector is represented at all. This would change when a working prototype was constructed.

Rendered in Steel

Among the conclusions of the preliminary study was a conviction that the conventional layout offered no advantages compared with the bullpup. Despite including a largely original Enfield design, it actually recommended that an existing weapon design be converted to a bullpup configuration and chambered for a cartridge in the 5-5.25 mm calibre range, advising that ‘…such a course of action would offer an adequate system at reasonable cost’. Although the chronology is unclear, it is thought that the next step was for Enfield to cut and reconfigure the two ‘real’ weapons seen in the video. In keeping with the rough design of the ‘Pattern B’ rifle, an AR-18 was modified into a bullpup configuration with the addition of a custom machined upper and lower receiver extension to the front. An elaborate scope mount was attached to the top of this, and a newly fabricated trigger and trigger guard were relocated to this assembly, along with a replacement hand-made wooden pistol grip. A lever safety was built into this new assembly, but the AR-18 selector was left in place at the rear to serve as a ‘change lever’ (British parlance). No attempt was ever made to move the fire selector to a more ergonomic position, a flaw solved in the Steyr AUG then under development in Austria, albeit at the compromise of including a two-stage trigger. An alternative approach would have been to include another long internal linkage bar, as is the arrangement in the later Israeli Tavor design. A machined buttplate was affixed to the rear of the AR receivers in place of the original folding stock assembly, and a similarly crude handguard completed the gun.

Meanwhile, a then-new Stoner 63A rifle was likewise converted, apparently into an approximation of a ‘Pattern B’ LMG, as it retains a Stoner 63A LMG bipod (this has been permanently clamped in the stowed position on this gun). Curiously, what appears to be a heavy barrel is actually a machined and threaded outer sleeve, apparently just to serve as a visual representation of the heavier barrel intended for the LSW variant. The weapon is fitted with an LMG trigger pack with auxiliary rear sear for open bolt operation. This may be the origin of the open bolt automatic operation of Enfield’s original LSW design. The architecture of the Stoner 63 seems to have lent itself better to bullpup conversion, as the receiver extension here is a simple U-shaped sheet steel trigger housing with a replacement pistol grip, the whole being attached below the existing upper heat-shield. A custom butt-plate replaces the stock assembly at the rear. Whereas the AR-18 conversion is missing its optical sight, this piece retains an EM-2 UOS sight in a custom mount. Both guns were provided with rudimentary trigger linkage wires which, due to lack of internal space, run around the outside of the magazine well.

The AR-18 Connection

Very little of these conversions was brought over into the first prototypes of the new weapon system. In fact, it might be argued that far from proving that the SA80 is simply a bullpup conversion of an AR-18, these guns showed that directly converting an existing design was not practical or cost-effective. Instead, the design illustrated in the preliminary study was selected for prototyping. The SA80’s AR-18-type mechanical heritage has drawn criticism, but seems to be a sound decision. Several other capable designs have drawn from the AR-18, including the Japanese Type 89, German Heckler & Koch G36, and US Remington ACR. Even the Steyr AUG is mechanically quite close. On the subject of design lineages it is noteworthy that, given that the lead designer on the new project (Sydney Hance) had worked on the EM-2 bullpup of the 1950s, absolutely nothing of that design was carried through to the new weapon. The two weapons share only a bullpup configuration and, consequently, an optical sight fitted as standard. Given the complexity and expense of the EM-2 design and period trends toward both multi-lugged rotating bolts and very small calibres, this is perhaps unsurprising. The EM-2’s moment had long passed.

More controversially, it is claimed that Enfield obtained AR-18 parts from the Sterling factory by means of deception. This seems unlikely given that the MoD had already purchased a number of AR-18 rifles for trial, and the Pattern Room possessed at least one example at that time. Enfield could either have cannibalised one of these, or requested the purchase of more from somewhere other than Sterling (if this was somehow seen as inappropriate). More definitively, the physical evidence does not support this claim. Observing notable differences in build standard, a partial serial number on the flash-suppressor, and using access to Pattern Room archives, the author has been able to identify the weapon as serial number 000159, produced in 1970 by the Howa Machinery Company of Japan.  In any case, Sterling did not start production of the AR-18 until 1975, by which time Enfield had moved beyond experimental conversions and was building its first prototypes of the design proposed in 1971. These two pieces were likely converted in 1972, the year after the preliminary study, but before the decision to move ahead with Enfield’s design with the first ‘00 series’ test weapons. After this point in the development process, there would have been no need to produce conversions such as this. Other versions of the Enfield conspiracy theory allege that stolen Sterling parts were used in actual prototype guns (stay tuned for the next feature – Ed.), but these are demonstrably of a different pattern, and not interchangeable with the AR-18. We seem to be dealing here with an urban myth rooted in the corporate rivalry between Enfield and Sterling. There is a grain of truth behind the myth; the new Enfield weapon’s components would have looked like AR-18 parts to all but an expert eye, which might in the re-telling easily lead to accusations that they were copied or even physically stolen. Additionally, Enfield may well have paid visits to inspect machinery or even obtained Sterling assemblies as is alleged by Steve Raw in his book The Last Enfield – SA80: The Reluctant Rifle, but if so it seems likely they did this in order to study modern manufacturing methods, not to acquire parts to build either this mock-up or any of their prototypes. After all, Enfield had little experience with modern pressing and welding techniques, and indeed this inexperience would be revealed during trials.

Another story alleges that this piece was made from an example captured from the Provisional IRA. This is plausible on the face of it given how roughly the grinding has been done. However, it is highly unlikely. For one thing, the Stoner conversion also has its markings ground away; this seems likely to have been an attempt by Enfield to emphasise that they had carried out the conversions and not the companies who had built the donor weapons. Clearly they were not attempting to hide what these weapons used to be, as this would be obvious to anyone with basic small arms knowledge. More importantly, Pattern Room records show that Howa AR-18 serial 000159 was already at Enfield in November the same year, making purchase by and capture from the IRA extremely unlikely. It is also documented that the UK MoD purchased a number of AR-18 rifles for evaluation purposes.

The final mock-up covered in the video relates to another SA80 legend. This is the supposed ‘joke’ by rival arms factory Sterling, of sub-machine gun fame. Enfield may have been the UK government’s preferred manufacturer, but Sterling was at the time the licenced manufacturer of the AR-18. Sterling, a commercial concern and rival of the state-owned Enfield, was bypassed by the government entirely. Enfield was, perhaps unsurprisingly, selected as sole manufacturer of their own in-house AR-18 derivative. Allegedly in response to this and the alleged appropriation of Sterling parts, Frank Waters at Sterling constructed this non-functioning bullpup example of their own AR-18 rifle. The intent seems to have been to reinforce the idea that Enfield’s new weapon was really just a hastily converted AR-18; an unlicensed appropriation of their and ArmaLite’s intellectual property. If true, this is somewhat ironic, as before receiving the licence to produce bona fide AR-18 and AR-180 rifles, Sterling had already produced the very similar Light Automatic Rifle and would soon (1976) develop another ‘legally different’ design in the Sterling Assault Rifle/SAR80. This was created even as Sterling was licence-building ArmaLites, as a way to strike a licencing deal direct with Singapore, free of fees and other difficulties associated with sub-contracting the ArmaLite design. Both Sterling and Enfield were free to copy aspects of Stoner/ArmaLite’s design, there being no patent protection on the relevant assemblies. Stoner himself was quite open about using Melvin Johnson’s multi-lugged rotating bolt and Sergei Simonov’s short-stroke gas piston.

The next phase of the project would be to produce working prototypes of Sydney Hance’s design; mechanically close to the AR-18 but otherwise an original Enfield product. These first examples of the ‘485 Weapon System’ will be the subject of the next in this ongoing series of ARES/Forgotten Weapons collaborative works.

Special thanks to the National Firearms Centre at the Royal Armouries, who graciously allowed us access to their world-class collection for this and other videos and photos.

 Stay tuned for a the next instalment in this series of posts and videos examining the history of the SA80 weapons programme, here on The Hoplite.

Note: The information in this article has been superseded by that published in Jonathan Ferguson’s important original research work, Thorneycroft to SA80: British Bullpup Firearms, 1901–2020. That book is available from the Headstamp Publishing website:

Remember, all arms and munitions are dangerous. Treat all firearms as if they are loaded, and all munitions as if they are live, until you have personally confirmed otherwise. If you do not have specialist knowledge, never assume that arms or munitions are safe to handle until they have been inspected by a subject matter specialist. You should not approach, handle, move, operate, or modify arms and munitions unless explicitly trained to do so. If you encounter any unexploded ordnance (UXO) or explosive remnants of war (ERW), always remember the ‘ARMS’ acronym:

AVOID the area
RECORD all relevant information
MARK the area from a safe distance to warn others
SEEK assistance from the relevant authorities