SA80 History: XL60 Series in 4.85mm

Armament Research Services (ARES) is a specialist technical intelligence consultancy, offering expertise and analysis to a range of government and non-government entities in the arms and munitions field. For detailed photos of the guns in this video, don’t miss the ARES companion blog post!

Once the basic configuration of the new British rifle was determined, the next step was to build a series of prototypes. The design that took form was basically a bullpup copy of the Armalite AR-18. The design team at Enfield were mostly senior draftsmen, with virtually no firearms experience among them. To make things worse, most of the design team was regularly rotated onto other projects, preventing them from developing any project experience on the rifle.

Several prototype batches were made (typically of a dozen guns each, both IWs and LSWs), all in the unique British 4.85x49mm cartridge, with a variety of different feature sets. Through the different patterns, configurations would change on the safety (push button vs lever) fire selector (push button vs lever), and magazine catch (straight-in side lever vs rock-in side lever vs rock-in rear paddle). At this time, plans still existed to make both left- and right-handed versions of the final gun, so prototypes of both were manufactured.

Because cost-cutting measures had not yet been forced on the project, these XL-60 series guns were generally reliable, at least in normal conditions. They are quite comfortable to fire, with a cartridge very similar to the 5.56mm NATO in practical terms. There is nothing particularly wrong with that cartridge, but it would be dropped when it lost NATO trials to the Belgian SS109…but we will address that in the next episode of the SA80 history.


  1. “The design team at Enfield were mostly senior draftsmen, with virtually no firearms experience among them. To make things worse, most of the design team was regularly rotated onto other projects, preventing them from developing any project experience on the rifle.”
    Was any research of existing bull-up fire-arms done? If yes what fire-arms were examined and conclusions, if not: why?

  2. Ah, the “semi-auto = closed bolt, full-auto = open bolt” rears it’s head once again!
    Seems like a pretty good deal, as usual, though I’m guessing having that leaves a pretty big opening for stuff to get into places where you want it, which is why they don’t put that feature in more rifles.
    On a scale of “not much of a problem” to “G11 space magic” how much more complex is that function compared to just using closed bolt for both semi and full auto?

    • I don’t know with the SA80, there are patents for some of the contemporaries.

      If my memory serves me right, I think they’re by people like Stoner and Sullivan.
      It was Sullivan who was the lease designer/developer on the AR18, and many other guns, including the Ruger 77 bolt action.

  3. It would be really nice to have a similar set of videos and insights into the FAMAS and AUG development process. Particularly the AUG, because that is probably the most successful of the three, all developed around the same time. There isn’t an awful lot that I’ve been able to find on the AUG development process, either. At least, not accessible in English.

    • You are right, success of AUG was without precedent – it worked and stayed in same configuration for long time, till dedicated scope was replaced with rail for greater universality. Behind its development were just 2-3 people who worked in mutual respect and unison.

      • “just 2-3 people”
        According to
        Kelly Johnson (designer of P-38 Lightning pursuit aeroplane), has created 14* rules to make working effective, amongst others is:
        The number of people having any connection with the project must be restricted in an almost vicious manner.
        * – anecdotal story, says that there was also 15th rule, which advise to avoid any business with navy at any price

  4. Video viewing troubles are over! (Looks like the chrome browser on android was the problem, a de blobbed firefox/iceweasel browser works fine).

    Parachuting generic engineers and draughtsmen in to do the job of designing and developing guns, is what Dupont did at the end of the war that made the world safe for Stalin, Mao, Pol Pot…

    Merle H (“Mike”) Walker did a decent job with actions, and he later recognized the problem with the trigger that bears his name. Unfortunately the Remington bean counters didn’t follow Walker’s recommendations, as they would have cost 5.5c more per gun.
    Lions lead by donkeys? Or just an example of Dunning Kruger?–Kruger_effect

    • “example of Dunning Kruger”
      There is word in Deutsch for individuals described here: Besserwisser

    • “Parachuting generic engineers and draughtsmen in to do the job of designing and developing guns”
      Requiring said to make working innovative pattern of weapon seems to be risky. But as example that it is possible might be SG machine gun, designed by Goryunov,Горюнов,_Пётр_Максимович
      V.A.Degtyaryov in his memoirs states that Goryunov, was machinist with good reputation, working at Kovrov plant, but through 15 years of cooperation, never shows himself as designer nor constructor. In Summer of 1942, Goryunov, ask Degtyaryov about model of machine gun he did, which impressed Degtyaryov.
      -When you made it – asked Degtyaryov.
      -I conceived long time ago, model done in recent, when I become aware of task for new mounted machine gun.

      • In old times it had been a routine perception that only people with relevant hands-on experience may be able to design something new. I encountered this view myself from older co-workers when I started in late 60s. However, now with advent of dynamic computer modelling and advances in norms of human engineering, these traits can be substituted for quickly and efficiently. On bottom of it basically thermodynamics with specific application. Did I mention ballistics.. 🙂

  5. Ian, you lucky, lucky git for getting to play with and shoot that! 😀

    Anyway, the funny thing about the SUSAT is that the tube itself is indeed bomb-proof, but the mount loses zero if you even look at it funny. At least on the production L85A1 I was issued with in my OTC playing soldiers days. Rezeroing was a constant PITA, and if you knocked it, zero was gone…

    • The optic and the mounting don’t match, the sight overhangs it, its obvious the mount was hastily cobbled on, the fact that it adjusts with nuts and bolts is a clue. The complete unit is ridiculously heavy and ruins the balance of the weapon.

    • I witnessed a rifle company that had convinced the higher up that they should ditch their optics that wouldn’t hold zero and go back to iron. Agreed. Problem. No one had thought to ask the troops if they’d ever shot a rifle without glass. The company shortly thereafter had a 7% pass rate on their qualification shoot. The computerized range was blamed and the next test was done on one with Hythe Lifters where cheating was vastly easier.

    • One of the complaints in the Handgunner “Service Rifle SNAFU” piece,. Was about the construction of the rail on the rifle.

      Due to the tolerances in pressing, the vagueries of welding, and stacking of tolerances due to construction from several pieces,

      There was very poor control of the height and alignment of the sight axis above the bore.

      This particularly revealed itself in Northern​ Ireland, where sighting was usually done on 25m indoor ranges. There was very little correlation between a first zero at 25m and where the bullet might or might not cross the sight axis after that.

  6. Maybe they didn’t get firearms people to built it because they basically gave some people a brief which was “make this AR180 bullpup”, and then thought what could go wrong. Of course making something a bullpup is quite complicated.

    They seemed to have done a good enough job, until they went over to mass production…

  7. This weapon shows how important it is to have the right people guiding the project along, the design seems to have been constantly fiddled with, ultimately turning a good design into a pigs ear. You can see the original prototypes were well designed and purposeful, but there was no one to keep the project on track.

    • Alas, politicians and miserly accountants cannot comprehend common sense from engineer’s perspective! Perhaps this is the reason why the AR-18 family failed to get adopted (cheap stampings as mandated for “third-world-country-friendly manufacturing,” complicated assembly due to AR-15 similarities, extremely loose tolerances that will eventually shake the rifle to pieces or let dirt get into action)? I’m pretty sure tons of AR-18 fan boys will attempt to tie me to a post and have me shot just to “refute” the weaknesses I mentioned…

      • “failed to get adopted”
        Modern Firearms:
        states that:
        The AR-18 was a really successful design from a technical standpoint, but it come out too late to compete with both officially accepted and adopted AR-15/M16 rifle of American origin and already widespread AK-47 rifle of the Soviet origin.
        So it was simply too late, as many potential export fire-arms, which failed to success.

      • Echoing Daweo,
        The AR18 was a very well worked out rifle.

        There’s nothing intrinsically wrong with pressed metal from a functional point of view, so long as the designer​ understands the material and how to mitigate the differences between bent metal and machined from solid construction. Or, construction from a die casting in the case of AR15.

        Compared to the AR15, the 18 has a tougher receiver, the bolt carrier runs on guide rods rather than running on, or touching bent metal (a la M3 grease gun) so slight denting of the receiver doesn’t necessarily put the gun out of action.

        I’ve not seen figures comparing bolt group life for the 15 and 18, but I would assume that having a piston rather than direct gas impingement, is going to result in greater bolt group life for the 18. That is certainly the case for whatever the H&k version of the AR15 with a piston is called, when It is compared to the AR15. It doesn’t blow all of its lubricant out, and doesn’t heat the bolt group. It also doesn’t blow crap into the fire control.

        The 18 also had a reciprocating bolt handle, which could be used to force a sticky case into the chamber, where it would likely get stuck… (Eugene Stoner did not like forward assists, and didn’t approve of the addition of a forward assist to the M16).

        I think the only actual patented feature of the 18, was the gas piston, and the spherical connection between the piston and the piston rod. This allowed the piston to find it’s own bearing and alignment inside the gas cylinder, without any misalignment or bias from the operating rod.

        That, in turn, allowed a much lighter operating rod to be used, as it doesn’t have to stay stiff. The AR18 gas system is therefore particularly light, and long lived. The weight which is saved can be concentrated in the bolt carrier, where it belongs.

        IIRC, the AR18 has a single centrally located recoil spring, and the two grease gun style guide rods, which enter matching holes in the trunion. The SA80 used dual springs mounted on the guide rods.

        There is something about the SA80 series having faster spring rates than the AR 15. British loading of the 5.56 complies with the STANAG, but gives higher port pressure than the united state loading.

        It has been found that using British loads in the M16 and the M4 carbine, results in cases stuck in the chamber, with the rim torn off, and with overspeeding of the bolt group (M4 operation is crappy enough already – but complaints are usually brushed away as being due to insufficient cleaning by insufficiently​ trained operators).

        united state military loads in turn, don’t have sufficient port pressure to reliably operate the L84 A2, when it starts to get dirty. So much for NATO standardisation.

        It does show that even with gas operation, reliable running of self loaders is very dependent upon ammunition being within fairly narrow limits of pressure and timing. Unless a rifle and ammunition are correctly matched and tuned to each other, poor results can be expected. Assuming correct matching with ammunition, an AR18 should be everything else being equal, more reliable and longer lived than an AR15.

        That said, there was some subtle confirmation of the level that the British state had descended to, that its military rifle was derived from a design to be manufactured in third world dictatorships.

        • The AR18/180 does not have a centrally located recoil spring. The 18/180’s dual recoil springs ride on the dual guide rods.

          Secondly, in military testing the H&K M27 had worse bolt life than the M4A1 (the study is mentioned in an article called “Why the M27 IAR is NOT the right rifle for the Marine Corps” if you care to dig for it). I feel it should be mentioned that the author of the piece misattributes the increased wear to the rifle being overgassed because of the gas port; this is wrong because though the gas port is the same diameter in all 416/M27/MR223/556’s regardless of barrel lengths, the gas blocks used in 14.5″ and up have a purge port to deal with the increased gas pressure.
          While it is true that the test was done with non-NATO spec ammo (M855A1), if the HK design really reduced bolt wear then the M27 should still have beat the M4A1 in this area.

          • Recommended bolt replacement interval for the M4 and M4A1 is 6,000 rounds.
            H&K technical terms of delivery for the 10.4 and 14.5″ 416 is a bolt life of 10,000 to 15,000 rounds.

            It would not surprise me in the slightest if the bolt replacement interval for the M4 is overly conservative (it’s more tax money to manufacturers).

            I had taken the differences to represent the 416 as more durable and longer lived than the M4.

          • Ok, I read the article.
            An anonymous source told the firearms blog…

            I’m not a fan of H&k, and the TFB piece read like a mercantilist pamphlet. Like you, I’m sceptical of the author’s engineering understanding. Lighter hammer springs have very little effect on the initial travel of a bolt carrier, and a slightly heavier bolt carrier and longer free travel before the bolt unlocks achieves a longer delay far more effectively.

            You’ve got my scepticism fired up about the whole stoner multiple lugs idea.

            The many tiny lugs have the advantage of only requiring a small bolt rotation, but carry the disadvantage of offering less confinement to the core of the lugs compared to two or three large lugs. So to that extent, problems of bolt life are inherent in the entire family, AR15, 18, SA80, H&k416…

            I need to re-visit, why Singapore Chartered Industries’ designs went to a two lug layout.

        • “(…)That is certainly the case for whatever the H&k version of the AR15 with a piston is called, when It is compared to the AR15. It doesn’t blow all of its lubricant out, and doesn’t heat the bolt group. It also doesn’t blow crap into the fire control.(…)”
          In this place, I want to note that direct gas impingement system gas, can be done to work properly, example is MAS-49 self-loading rifle:

          which in lighter version (MAS-49/56) served until it was replaced by FAMAS.

          • AR-10/AR-15 ‘direct gas impingement’ doesn’t have a great deal in common with the other two successful gas impingement service rifles, the MAS-40 family and Ljungman’s AG-42 and clone. In the latter two, once the gas from the gas tube impinges upon the bolt carrier, it is free to fill large open-architecture receivers and is swiftly expelled when the action opens. Conversely, I’ve heard pedants describe the AR-10/15 action as a sort of in-line gas piston action, the bolt carrier itself being the piston- semantics aside, that’s certainly going to have implications for where the gases leave the weapon and where they deposit their precipitates.
            We argue about AR-15 reliability like it’s our job- is it inherently less reliable, or unjustly maligned, Damned McNamara et cetera- but I’ve only ever heard glowing praise for the MAS-49/56. I know a fellow who can’t get his Hakim to run right, but I suspect it’s not the gun’s fault and won’t count that as a strike against Ljungman’s design.

  8. I strongly suspect that the EM-2 (, whose inivoative/novel .280″ Enfield cartridge lost out to the 7.62mm NATO round, had some influnce on the bullpup design. i think its also important to note that the bullpup AR-18 was made by a UK based company, Sterling, who had licensed the production of the AR-18 in the UK.
    As an aside, if anyone knows the location of a surviving Sterling bullpup AR-18, it would be very interesting to have some photos, please.

  9. Say if the Stoner 63 was used to develop the SA80, would it have been a more reliable platform?

    • It would almost certainly have been sturdier. Although the problem with the L86 disassembling itself spontaneously by shearing its assembly pins was a materiel’ problem, not a design goof. Ditto the easily broken forend that allowed the recoil spring to depart downrange.

      If the pins had been properly made (I’d suggest 4140 with annealing and case-hardening), the sockets had been done properly (case-hardening again), and the forend had been of better material (believe it or not, old-fashioned Tenite would probably have been the best choice), the only major problem would have been that effed-up SUSAT.

      And the best cure for that would have been an M16 type carry-handle/rear sight deck setup, with an elevated front sight post- and an ACOG attached firmly to the carry handle.



      • “L86 disassembling itself”
        This is only yet another proof, that military fire-arm, need to be tested carefully, before adoption.

        • And if some dumb bureaucrats changed requirements after a successful pre-production batch passed tests? M16 was marred by penny-pinching congress who threw away the chromed barrel and bought really cheap ammunition with really corrosive propellant!

          • That was the Army’s Ordnance people going over to ball powder without testing the new loads before issuing them. Whoever did so apparently covered their tracks well enough to avoid congressional inquiries. The crommed chamber and bore has been attributed to Secretary McNamara who probably thought they were just trying to stall the new rifle.

          • “threw away the chromed barrel and bought really cheap ammunition with really corrosive propellant”
            I am not sure what approach U.S. designers chose most often, but in Soviet Union cartridge and fire-arm were often considered system, of which all elements should be tested.
            Anyway it should be remembered that Greedy Pays Twice

      • you can’t really fault the SUSAT for its time

        back when the L85 and L86 were first introduced Britain was one of the (maybe even the only) military to give every soldier a telescopic sight.

        • Austria starts getting the AUG into the hands of the Bundesheer sometime in 1978, seven years before the SA80 becomes L85. Compare and contrast the SUSAT and the AUG’s 1.5x Swarovski optic: both rugged fixed low-power sights with simple reticles and passable backup irons, but one was pretty clearly conceived as part of a complete system and we’ve been hearing a lot about the shortcomings of the other for want of the same.

          Echoing Kirk above, a comparison between the developmental families of the SA80, the FAMAS, and the AUG would be thoroughly revealing. Broadly similar- 5.56 bullpups conceived in the ’60s- they come from three very different paradigms of small arms and the infantryman. As far as I know, there’s not an awful lot in the public domain about the development of the FAMAS and less still re. the AUG; I’ve seen black and white photos of a few FAMAS ancestors, but I am completely ignorant of the AUG story.

    • The bolt of this weapon very closely resembles that of the Stoner 63, including the massive cut out for the extractor. Could it actually be one?

  10. In spite of perceived or true misgivings, this series of British rifles was, in my estimation the break-thru in firearms design. In some way I consider these better that what followed and became SA80/85.

    These and other bullpup rifles are described in book by T.B.Dugleby named modern Military Bullpup Rifles. I recommend to obtain it to anyone who is interested in this particular development. There are among comparative graphs of various cartridges and their optimisation vis-à-vis rifles.

  11. Very informative and interesting.

    Ian, thanks for giving us “armchair guys” a vicarious thrill watching you shoot the original 4.85x49mm IW prototype! Seems–like you stated–a nice, svelte little rifle… How things went so very, very wrong in the actual implementation of the 5.56mm version awaits. And should also be very interesting.

    So, do I have this right?
    a. EM-1 too heavy
    b. EM-2 too expensive and not dependent on USA, which had been crucial to the UK in WWI and WWII, hence the move from bolt action No.4 and Bren and Sten to L1A1 SLR, Bren/FN MAG, and Sterling… Instead of EM-2, Taden, and EM-2 and/or m/50.
    c. IW not 5.56mm SS109, and to be continued…
    d. SA80/L85 TBA…Stay tuned!

  12. A great video. I was thinking this morning about how the safety catch lever worked on the prototypes and now I know. And yes a great looking weapon. I’ll look forward/search out other videos. Thanks.

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