SA-80 History Part 4: Final Prototypes – It Ain’t Looking Good

Sometimes it’s good to see what the trainwreck is going to look like before the train comes off the rails and wrecks. Some might call this troubleshooting, but the British government would call this the final L-85 and the L-86 prototypes, the XL-85 and XL-86, respectively.

Compared to the XL-70, the weapons exhibit few larger changes and mostly boil down to General Dimensioning and Tolerances (GD&T for those in engineering fields). Recognizing that a main enemy of weapons function is the ingress of debris, the Enfield engineers set about tolerancing the interface between the bolt carrier and the body of the weapon.

**Side note – for a great example of why keeping stuff out of a weapon is a big deal versus being able to function somewhat with it in, check out InRange TV’s mud tests of the M16 and AK-47, respectively.

The other main change was to the magazine body. Instead of the poor choice of a separately tacked on the magazine well, the designers opted for a completed magazine well that was welded into the body as a complete unit – much better for holding tolerances.

But, they could not solve a major issue of weapons having “split groups” or differences in POI when the weapon is in semi-auto versus fully automatic fire. The L85 would split groups, sometimes even significantly, when used on full-auto – which was a major problem for the Light Support Weapon version.

For the full details, check out Forgotten Weapon’s video on the L85, part 4 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.

Nathan can be reached at Nathan.S@TheFirearmBlog.com

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


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  • forrest1985

    “Sometimes it’s good to see what the trainwreck is going to look like before the train comes off the rails and wrecks. Some might call this troubleshooting, but the British government would call this the final L-85 and the L-86 prototypes…” Brutal, but 100% on the money with that statement!

  • CJS

    L86a2 has split groups.

  • gunsandrockets

    It is what happens when non-gun engineers and bean-counting bureaucrats join forces to design a firearm.

    I wonder. Is that FUBAR also the inevitable result when a nation’s gun-culture is dying?

  • Rocky Mountain 9

    The “most read” section at the bottom of the page has been broken for months, no longer showing up-to-date articles. I figured y’all would catch it by now, but it continues. Could you please repair this function? I enjoyed it for catching up on TFB’s most interesting articles of the day.