N.B. As of November 2019, there is now a more comprehensive article about L119A2 parts and accessories

It’s been observed that there are two distinct variants of the L119A2 in use with UKSF.

They are popularly defined by their uppers, although the differences between the two concern the kit-out of the lower as well:

A. “IUR” – Partial RIS; available in 10” and 15.7” barrel lengths
B. “Alternative IUR” – Full RIS; 10” barrel length only
Features Common to both the Partial RIS “IUR” and Full RIS “Alternative IUR”

The following basic package is thought to be shared by both the Partial RIS “IUR” and the Full RIS “Alternative IUR” versions of the L119A2:

  • Magpul CTR stock
  • Original Ergo grip (not Ergo 2)
  • Geissele trigger group
  • Colt Canada standard trigger guard
  • Colt Canada ambi selector group
  • Various Colt Canada ancillaries including BUIS (both folding and fixed), QD sling swivel, sling mount and grenade adaptor attachment
A. Partial RIS “IUR” Features
  • 10″ and 15.7″ barrel lengths (not 10.5″ and 16″)
  • Surefire FH556-216a flash hider
  • Colt Canada ambi mag catch
  • Colt Canada ambi charging handle (two types)
  • Magpul ASAP
  • Grenade lug tapped for barrel nut anti-rotation bolt
  • Plug removed from Original Ergo grip
B. Full RIS “Alternative IUR” Features
  • 10″ barrel length only (not 10.5″)
  • Birdcage flash hider
  • Standard Colt Canada mag catch
  • Standard Colt Canada charging handle
  • Magpul ASAP-QD
  • Grenade lug not tapped for barrel nut anti-rotation bolt
  • Plug often retained in Original Ergo grip
Upper Receiver Serial Number

While the Full RIS ‘Alternative IUR’ exhibits the LMT patent number, the Partial RIS ‘IUR’ is said to be shipped blank. It apparently is subsequently engraved with the lower’s serial number (in full or part) by UKSF armourers.

The style of engraving is said to vary, with the blog currently able to verify white laser etching and deep engraving. The white laser etching appears to be close spaced Arial.

The format displayed on the white laser etched examples appears to be the full serial, which is a concatenation of:

Year of production (2 digits) + month of production (2 digits) + production unit (3 digits) + country code (GB)



NOT A REFERENCE PIC – HAO replica L119A2 receiver set with an example upper receiver serial number, matching the stamped serial on the lower
NATO Stock Number – NSN

The L119A2 exhibits a NATO Stock Number – or NSN – on the right hand side of the mag well (although this is sometimes lacking in newer pics).


In the above pic we can just about make out an NSN which exhibits this string:


Other, less public pics clearly confirm this number.

According to the table below – from the L119A2 PAM – which was publicly posted on Facebook, the string ending 98 corresponds with the 15.7” model.

However, at this date I would be inclined to use the 98 number on a replica lower for either length upper. This is because, so far, I have only seen lowers with NSN markings ending 98 – regardless of upper.

The 99 lower may well be out there, or the NSN could have been created and never used. Time will tell (or we may never know).


Also note that 16” (as related above) is an approximation, not the defined length of the rifle length IUR’s barrel (which is 15.7″).

There is no documentary evidence that I know of which suggests a different length for the SBR version of the IUR, so this is always taken to be 10″.

Charging Handle Latch

In the wild, some older L119A2 charging handles have had their existing latches cut down.

NOT A REFERENCE PIC – ghettoed real steel Colt Canada charging handle installed on HAO replica L119A2

However, it was confirmed in September 2020 that newly issued A2s feature a shorter version of the latch. Read more.

RS, but not a reference pic
Staked Receiver Extension Nut

Similarly it was revealed in September 2020 that the ASAP is indented with a punch, as a receiver extension nut anti-rotation measure. Read more.

Monolithic Design

The L119A2 exhibits a monolithic upper, meaning that the rail and upper receiver are conjoined in one continuous unit. It is referred to as IUR – which means Integrated Upper Receiver.

In 2016, I pointed out that  LMT owns the patent on monolithic uppers and that they successfully prevented Mega Arms from marketing their own one-piece upper.

It later became apparent that Colt Canada had officially licensed the monolithic upper receiver design from LMT, as evidenced by the US Patent number shown on the Partial RIS ‘Alternative IUR’ L119A2.

See the patent PDF here.

Contextual Information

The pic below – from The Sun newspaper in May 2016 – was the one which absolutely confirmed that the L119A2 was in use with UKSF. The pic is from Exercise Winchester Accord.

 photo 11f014b9-3fc1-45c9-8eb2-1e42c0946981_zpsusfimk87.jpg

The following images are legacy screenshots from Colt Canada’s website, which were used at the time to cross-reference with the Winchester Accord pic, in order to better understand the parts composition of the L119A2.

Needless to say, additional information has come to light in the past few years.

Screen Shot 2016-05-12 at 16.20.53_zpscrvrq2z7
Screen Shot 2016-05-12 at 16.21.17_zpsimx3pb6t

Colt Canada’s website has also been updated:

More articles relating to the L119A2:
  • The Comprehensive UKSF (SAS/SBS) L119A2 Parts and Accessories List
  • GG&G AR15 vertical fore-grip in use here
  • Magpul QDM and ASAP QD in use here
  • 15.7″ L119A2 upper in use here
  • Surefire FA556SA Suppressor here
  • GG&G Aimpoint T1 mount in use here
  • Magpul MS3 sling in use here
  • Magpul ACS stock in use here
  • Colt Canada parts – as used on the L119A2 – here
  • Manta Very Low Profile Rail Covers as used on the L119A2 here
  • UKSF Newcastle raid pics part 1
  • UKSF Newcastle raid pics part 2
  • UKSF Nairobi Kenya incident L119A2 parts breakdown here
  • UKSF Belize ‘Jungle Set-up’ L119A2 parts breakdown here
  • Confirmation bias (and the HSP Thorntail offset light mount) here
  • UKSF Ecosystem: S&S Precision Sling Clip – Old Gen – here
  • Inforce WML-type lights in use here
Illustrative Pics


partial RIS


Note: November 2019

Since May 2016 when this article was originally published, I’ve done my best to keep it refreshed with L119A2 updates. I’ve learned about these through my own research and from the research of friends (often with legit contacts).

However, since most enthusiasts aren’t particularly interested in the Full RIS ‘Alternative IUR’, this article has for the most part been superseded by:

The Comprehensive UKSF (SAS/SBS) L119A2 Parts and Accessories List


Big thanks to Jay Taranis for his help in the earliest stages of this article’s evolution.

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