EVOLVING CARTRIDGES AND PROCESSES
“Firearms technology itself has not changed dramatically in recent years,” Miles explains, “but there is now a much wider range of cartridges in use than in the past.” Where once British military requirements centred largely on 5.56mm, 7.62mm and .50 calibre, today proofing must also account for calibres such as .338 Lapua Magnum and 6.5mm cartridges.
The London Proof House, working within the Commission Internationale Permanente (CIP) framework, maintains proof pressures for this expanding list, ensuring that every weapon can be tested with the correct ammunition.
In the past, military proofing was closely associated with the Royal Small Arms Factory, where the Proof House operated a branch facility until 2003. Today, proofing is carried out at manufacturers’ sites, at dedicated ranges, or within the Proof House itself. Miles notes that logistics often dictate these choices: “If firearms destined for the UK military are made in the USA, it makes sense to test them there rather than wait until they’ve been shipped across the Atlantic.”
RIGOROUS SAFETY MEASURES
Military proofing goes beyond firing an overpressure round and inspecting the weapon by eye. Non-destructive testing (NDT) methods such as dyes or electromagnetic techniques are frequently employed to identify flaws invisible to standard gauges. “It’s a very thorough way of testing,” says Miles, “and ensures that firearms not only withstand the proof load but are structurally sound for service use.”
The process draws on a mixture of standards. For small arms, the UK Rules of Proof 2006 are combined with Ministry of Defence Standard 05-2005, alongside current CIP decisions. Larger calibres, such as 20mm cannon, bring in additional frameworks, but for small and medium arms this crossover of national, military and CIP standards underpins testing.
ON-SITE PROOFING AND SUPPLY CHAINS
Conducting proof tests away from the Proof House requires strict controls. Manufacturers must provide secure proof areas with ballistic protection, lead-safety measures and insurance compliance before tests can be authorised. “I rarely encounter unsafe facilities,” Miles explains, “but each site is carefully risk-assessed before work proceeds.”
Historically, proofing was often embedded within the production line to avoid slowing supply. The East India Company, for instance, once built premises next door to the Proof House to speed exports, while the Royal Small Arms Factory housed a branch proof operation to process vast numbers of SA80 rifles.
Even today, large batches of firearms can be processed in short timeframes by small, experienced teams. Flexibility remains essential, with proof staff travelling to overseas factories or UK production sites when required.
PROOF AMMUNITION AND QUALITY CONTROL
Military proofing often requires bespoke ammunition. Civilian proof rounds are widely available, but for larger calibres or less common cartridges supply is limited. Specialist ammunition makers therefore manufacture proof cartridges under strict conditions, drawing on ISO 9001, ISO 17085, NATO and Ministry of Defence requirements.
ISO 9001:2015 also underpins the London Proof House’s operations. “It doesn’t dictate our proof processes,” Miles says, “but it governs how we conduct them.” Every stage, viewing, gauging, firing, marking, follows established procedures, audited regularly to ensure compliance and consistency.
RAPID, FLEXIBLE SUPPORT
Meeting Ministry of Defence and NATO requirements demands foresight. The Proof House maintains strong supply chains for proof ammunition across all military calibres and monitors defence procurement projects to anticipate demand. Staffing and logistical plans are put in place ahead of schedules, ensuring testing can proceed without delay.
Awareness is also critical. High staff turnover in procurement and defence organisations can lead to knowledge gaps, so the Proof House makes a point of maintaining close ties with the Army, the MOD and private contractors. “We are always making our presence known, so people know where to come for proof solutions,” Miles explains. Many serving and retired soldiers from the Army are members of the Gunmakers’ Company connected to the London Proof House. Their presence offers both important networking links and practical support in the area of proofing.
HERITAGE AND INNOVATION
The fundamentals of proof, inspection, measurement, over-pressure testing, reinspection and marking, remain unchanged since the seventeenth century. What has evolved are the methods and technologies.
Where proof marks were once hammered into steel, high-precision lasers now engrave cleanly on aluminium, titanium and polymer. Sound moderators, increasingly made from thin alloys, cannot be stamped in the traditional way and are instead laser marked.
Black powder proof loads of the past relied on weight and volume. Today, nitro cartridges demand precise pressure measurements using calibrated equipment. Modern proof ammunition is developed with advanced pressure barrels and digital systems that far exceed earlier techniques.
FUTURE TRENDS
Looking ahead, Miles expects military proofing to reflect the continuing diversification of service weapons. “In the past, you might have seen two or three standard calibres,” he says. “Now there are more, perhaps six or seven, and the challenge is to respond quickly to new cartridges as they are adopted.”
Military proof has long accounted for a significant proportion of the London Proof House’s work, although activity varies with procurement cycles. Demand peaks when new rifles or calibres are introduced and quietens once production stabilises. Nonetheless, the overall requirement for proofing remains steady, underpinned by operational needs and modern conflict.
For the London Proof House, the task is to remain both a guardian of heritage and a responsive partner within the UK’s wider proofing framework. “The principles are the same as they were centuries ago,” Miles concludes. “But the tools and the standards have moved forward. Our job is to make sure every firearm that leaves for service is safe, effective and ready for use.”
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