Illustrative: a soldier aims an SA80 (L85) rifle during multinational close-quarters training in Poland, June 2026. U.S. Army photo by Staff Sgt. Emilie Lenglain, V Corps, via DVIDS (public domain). Image does not depict any programme candidate weapon.

UK Small Arms Modernisation: Four Projects Running in Parallel, One Unanswered Calibre Question

Technical Summary

The United Kingdom Ministry of Defence (MoD) is modernising infantry small arms through four separate lines of effort at the same time. Project Grayburn is the assault rifle replacement for the SA80 (L85) family, sized at 150,000 to 180,000 rifles across five variants on a common lower receiver. Project Shamer is the multi-calibre sniper system to replace the L115 and L118. Project Troubler is a lightweight 5.56x45mm NATO assault machine gun for dismounted troops, weighing under the 7.1kg of the retired L110A2. The fourth line is the 7.62x51mm NATO L7A2 general-purpose machine gun (GPMG), long tracked under the notional Project Cairns replacement, which took a decisive turn in June 2026.

That June turn is the near-term news. Rather than compete a GPMG replacement, the MoD moved to sustain the L7A2. Heckler and Koch (H&K) UK was set to receive a ten-year contract worth about 70 million pounds including Value Added Tax (VAT), just under 58.4 million pounds before VAT, to supply weapons in the L7A2 Mid-Life Improvement (MLI) configuration from Nottingham, without competition. Read as a portfolio rather than four unrelated tenders, these programmes share one question that none of them formally answers: whether the British Army should keep its split 5.56mm and 7.62mm calibre structure, or move toward a single intermediate cartridge such as the 6.5x43mm Lightweight Intermediate Calibre Cartridge (LICC).

Project Grayburn seeks between 150,000 and 180,000 rifles across five variants on a common lower receiver, with an envisaged contract period running from April 2028 to March 2045. Find a Tender, Project GRAYBURN concept notice (2026)

Analysis of Effects

The calibre question is where the four programmes intersect. Today the infantry section carries two families of ammunition: 5.56x45mm NATO for the rifle and the light machine gun, and 7.62x51mm NATO for the GPMG and the designated marksman. The 6.5x43mm LICC, developed by FN America from the earlier .264 USA work of the US Army Marksmanship Unit, is engineered to deliver something close to 7.62mm terminal performance inside a package near the size of 5.56mm. FN has delivered two prototypes to the US Irregular Warfare Technical Support Directorate (IWTSD): an individual weapon system and an assault machine gun built on the FN Evolys. The stated draw is a stainless-steel-cased round roughly 20 percent lighter than a brass equivalent, with a flatter trajectory and better retained energy at range.

The barrier is standardisation, not physics. NATO logistics run on the 5.56mm and 7.62mm STANAG rounds, and a national move to a third combat calibre would sit outside that framework until a NATO Standardization Agreement existed. Canada has begun pursuing exactly such a STANAG for 6.5x43mm alongside at least one other member, which is the first sign the calibre could gain alliance traction. The L7A2 decision cuts the other way. By taking the GPMG down a sole-source MLI route under the single-supplier provision of the Procurement Act 2023, the MoD has locked 7.62mm GPMG capability in place for another decade. That choice narrows, for now, the space in which a single-calibre argument could be applied across the whole section. The contrast with the United States is instructive: through its Next Generation Squad Weapon (NGSW) programme the US Army selected a heavier 6.8x51mm Common Cartridge for the M7 rifle and M250 automatic rifle, fielded from March 2024, an overmatch route that trades carried weight for penetration. The LICC case for the United Kingdom rests on the opposite logic, a lighter round that eases the dismounted load while still improving reach over 5.56mm.

Personnel and Safety Considerations

These are procurement programmes, not incidents, so the safety frame is qualification and sustainment rather than disposal. Service small-arms ball ammunition is typically stored and transported as Hazard Division 1.4, Compatibility Group S or C, a low-consequence classification, but any new calibre still requires a full safety and suitability for service qualification before fielding, covering pressure, function across the temperature envelope, barrel life and suppressor interaction. The human-factors case for an intermediate round rests on lower recoil impulse improving first-round hit probability and shortening the path to proficiency for recruits, a claim that vignette-based trials, rather than pure compliance testing, are best placed to confirm or refute.

Data Gaps

Several load-bearing points remain unconfirmed in open sources as of 7 July 2026. The Project Troubler award outcome has not been announced, despite a contract start date that has now passed. The Grayburn calibre decision, 5.56mm versus a more lethal successor, is explicitly still open. The expanded Shamer contract value, reported at around 20 million pounds against an original 1 to 4 million pound estimate, is not independently confirmed. No open source establishes that the British Army has formally evaluated the 6.5x43mm LICC. Exact unit quantities, prices and in-service dates across all four programmes are treated here as estimates, not confirmed figures.

Corrections & updates welcome. If you hold open-source data that refines or corrects any parameter in this article, please contact [email protected] citing the specific claim and your source. Verified corrections will be incorporated and credited in the revision history. AI-assisted technical assessment based on open-source material. Not a formal intelligence product.