SA80 History – Part 2 on the XL60 Series & 4.85mm Chamberings with Forgotten Weapons

Often more fascinating than the weapons developed is the history of developing weapons. In almost all cases, weapons are frought with initial troubles, constantly moving mechanical targets, and perhaps most trouble – politics. While today’s politics is well outside of TFB’s purview, its always enjoyable to look back at their influence on weapons – a prominent example being the AR-15. However, we are not alone in politics having a large hand in development and adoption. It would seem the UK bequeathed that tendency upon us – the US being a former British colony and all.

Ian over at Forgotten Weapons has been on the historical trip of my dreams, spending time at the National Firearms Centre in Leeds, UK. There, he has been hands-on with the L85 or SA-80 series of weapons exploring their complex history and development choices. In the latest installment, Ian spends time reviewing the development in context of calibers and the eventual adoption of the US-sponsored 5.56mm NATO over the British 4.85x49mm cartridge.

Once past the basic concept, the UK development team moved on to the first round of prototyping. Trying to balance the needs of the general trooper while making a sufficient loading for a light machine gun, the UK team started with the home-grown 4.85x49mm – with similar performance to the 5.56.

In this installment, the weapon is starting to take shape, with the developers moving between a variety ergonomic options. For the full details, check out the video from Forgotten Weapons below:

Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • PK

    Fascinating stuff. I had, until now, zero awareness whatsoever of the 4.85x49mm British cartridge.

    The more I read and learn about various trials in Western nations, the more I agree with the general idea that NATO standard cartridges are what they are largely due to the USA picking which cartridge to use.

    • Mike

      Let the Americans pay for the R&D. They are always going to pick their own design anyway

      • PK

        That is rather the impression I’m getting, yes.

  • Major Tom

    Fraught not frought.

  • Gary Kirk

    Can anyone enlighten me as to what the chamber pressure was with the 4.85×49??

    Sounds like a throat burner to me, could be wrong..

    • Graham2

      52,000 PSI, which seems OK to me.

      • Gary Kirk

        So, roughly the same as m855

        • ostiariusalpha

          Labbett & Meade is the best source for information on British ammunition prototypes. They tested at various pressures, even going up to 57,290 PSI, but settled on the 52,000 PSI operating pressure.

          • Gary Kirk

            Thanks, and again, same as m855


    You guys know I’m not the smartest one posting here, but can anyone enlighten me as to why Ian has done three or so videos related to this series of rifles?

    • DW

      1. They are all but forgotten to most shooters
      2. Ian was in Uk for a while and visited ARES, where these guns are, so he covers them
      3. The whole SA80 development was tragedy on an epic level arguably only surpassed by the INSAS, people need to know where they done wrong.

    • CJS

      There’s 9 videos in total, from mock-ups to potential A3 uppers and from straight pull cadet rifles to carbines.
      It’s actually very interesting, would have liked to know more about how we went from the potentially good xl64 to the shambolic redesign that was the xl70 and xl85, but overall a well presented series.