Calibre interview: Paul McDonald, CEO of Heckler and Koch UK

As DSEI 2025 nears, Calibre Defence met with Paul McDonald, CEO of Heckler and Koch UK, to learn more about the company’s approach to Project Grayburn, the British MoD’s plan to replace its assault rifles.

In the early 1990s the Royal Ordnance Nottingham Small Arms Factory was putting the finishing touches on the initial production run of SA80 assault rifles for the British Army. The new 5.56 mm bullpup design was set to replace the 7.62 mm L1A1 SLR (self-loading rifle), which had been in service for close to 40 years by the time the last SA80 was produced. The SLR was known for its accuracy and hitting power at range, providing the ability to punch through trees that enemy soldiers were hiding behind. But it was also long and required extensive maintenance, the SA80 was therefore meant to be more suitable for vehicle-led operations by adopting a bullpup design (which means the magazine is behind the trigger) and by offering improved performance. 

However, the SA80 quickly built a reputation for being unreliable and finicky. The British MoD called in Heckler and Koch to upgrade the weapons, bringing 200,000 of them to the SA80A2 standard between 2001 and 2006. At that time, it was expected that the out of service date for the SA80 would be 2015, a date that was obviously missed, and so Heckler and Koch upgraded some of the weapons again, to the SA80A3 standard. Now, the British MoD has a project to replace the rifle, which has proven itself in multiple conflicts to be reliable and capable. That procurement is called Project Grayburn, and SIG and Beretta Defence Technologies UK have already positioned themselves as contenders (offering the MCX and NARP respectively). They are not alone however, with Heckler and Koch UK planning to build upon its already strong position to compete for the project, as Paul McDonald, CEO of Heckler and Koch UK explained during a July interview. 

Project Grayburn, not quite the end of the SA80

As Calibre Defence currently understands Project Grayburn, the procurement is understood to be unfunded. This means that the SA80A3 will likely have its out of service date (OSD) extended. “So there is an obsolescence plan needed, maintenance and support for the SA80 are needed,” Paul explained on a July 15 phone call. The officially stated OSD for the SA80 is 2030, which means the youngest rifles will be 36 years old. “The lower receiver is the governing factor in reaching the OSD, you can only repair it so many times,” Paul explained. The lower receiver houses the trigger mechanism and magazine housing, as well as several other key components of the rifle, the upper receiver contains the bolt carrier group and barrel. 

This essentially means that the SA80 must be replaced; it is no longer possible for the MoD to further delay this programme, which is already ten years behind its expected replacement. Some other weapons have been procured for special forces units, like the MCX from SIG Sauer for the Royal Marines, but only in the low thousands. “The MoD is looking at 100,000 weapons as a minimum and whatever they buy, it should have to do everything the SA80 does today,” Paul explained. The SA80 has a variety of configurations including a carbine version with a shortened barrel for vehicle operators and boarding crews, a cadet general purpose rifle for the UK’s cadet forces, a .22 calibre conversion for target practice,  and also the Army winter sports patrol race. 

Heckler and Koch UK and the MoD

In Paul’s opinion, Grayburn is much more than a replacement for the SA80; “It won’t just provide weapons, it will include through-life maintenance and improvement. It’s a 20-30 year programme.” This is perhaps why so many vendors are positioning themselves to address it. But domestic, end-to-end production is likely to have a significant weighting within the programme as it is a key driving factor of the Labour Government’s industrial policy. 

“Heckler and Koch UK already has the infrastructure in place in the UK to keep the SA80 running, so we would be positioned to maintain it until its OSD, but we can also build on that infrastructure to re-establish a factory here for Grayburn,” Paul explained. “Would building a factory add cost per rifle? It depends on whether or not that factory can support other global sales, and how much the company in question is willing to diversify and speculate in their manufacturing,” Paul explained. “For example, there isn’t much difference in size between the component parts for a 7.62 mm and a 5.56 mm rifle, so you could produce from the UK for your global supply chain,” he continued.

Additionally, Heckler and Koch is regarded as a global leader in small arms barrel production, which combined with the company’s established history of supporting the MoD puts Heckler and Koch UK in a strong position, Paul believes. 

Project Grayburn requirements

The question of calibre is a hot one right now, and the US Army’s shift to the 6.8 mm round for its assault rifles and support weapons is hanging over many small arms procurements in Europe. This decision is a complex one, but in short the regular 5.56 mm round is unable to penetrate modern ceramic body armour at any range. However, as procurement is often more politically charged than some might realise, it is not clear if or when the rest of NATO will follow the US. 

For the time being, it is likely that the UK will continue with the 5.56 mm calibre round. Despite lacking penetrating power against body armour, it remains effective for the types of engagement that are common in modern conflicts: Close, sharp, and fast, rather than at longer ranges. The calibre also speaks to the likely sequencing of Project Grayburn; once a weapon system has been selected, it is probable that the first rifles will come from a foreign production line, whilst a UK factory is established if required. This means the selected weapon system will have to comply with all existing legislation and requirements, rather than a brand-new calibre that would then have to be qualified.

“A mid-life upgrade could change the calibre, and it does seem that the MoD wants to be able to change calibre within the same system, which is very difficult from an engineering perspective,” Paul added. He did, however, emphasise that there is no system requirement at the moment.  “The MoD doesn’t want to funnel requirements so tightly that it throttles innovation and the scope for Grayburn is quite open at the moment,” he said. “With an open scope we could submit the HK416 and HK433. 416s are in use with France, the US, Germany, and Norway, so it is quite a global weapon that is proven to work,” he said. 

Calibre comment 

Much of the defence industry that looks at the UK is waiting for the Defence Industrial Strategy, which is expected in September 2025 and will reveal the MoD’s procurement priorities and the money that will be put into them. However, as a result of at least 15 years of declining investment, there are now so many capabilities that are going out of service and must be replaced, that it is difficult to see how they will all be funded. Project Grayburn is yet another project that must take place, or the need will become increasingly desperate. Fortunately for the British Armed forces, there is a healthy array of companies positioning themselves to address this need; with a strong competitor pool to pick from, it should be possible to secure a working and effective solution without excessive cost. 

By Sam Cranny-Evans, published on August 5, 2025. Credit for the lead image is Corporal Nanda Atherton, RLC/UK MOD © Crown copyright 2025. It shows a Brunei soldier using an oil bottle to maintain his issued SA80 A3 during Exercise Brunei Jungle Warfare Skills Meet. Heckler and Koch provided the upgrades to the original SA80, bringing some of the rifles up to the A3 standard.