THE ORDNANCE BOARD AND ITDU TRIALS
The Ordnance Board trials were intended to identify technical problems for correction before series production, and ran in parallel with the User and Troop Trials. Weapons were put through a number of tests including mud baths, drop testing and sustained-fire reliability tests, as well as being exposed to extremes of heat and cold. The methodology used would be criticized later by the Cabinet Defence Select Committee, for being too ‘clinical’ and using environmental chambers rather than testing how the weapons would actually be used by soldiers. For example, the icing tests were conducted by spraying the weapons with water in a freezer, which failed to replicate the effects of wind-driven snow clogging every opening in the weapon when troops actually deployed with it to Norway. Reliability was defined by ‘Mean Rounds Between Failures’ (MRBF), with a target of 2,500 rounds for the IW and 8,000 rounds for the LSW; the latter figure was obviously very ambitious, since the LSW had essentially the same mechanism as the rifle. Failures were classified into three categories:
(1) ‘Minor’ incidents could be rectified by the user employing the standard ‘Immediate Action Drills’, e.g. re-cocking the weapon to load a new cartridge after a misfire;
(2) ‘Serious’ incidents could be rectified by the user but needed more action, e.g. by stripping and cleaning the weapon to remove excessive fouling;
(3) ‘Critical’ incidents could not be rectified by the user, e.g. parts breakages.
The MRBF calculation counted only critical failures. While this was not intrinsically wrong – any MRBF target including the less serious categories would have necessarily been much lower – it did have adverse consequences. Since nothing except critical failures affected the MRBF target, the other categories were essentially ignored and little attention was paid to rectifying the causes, no matter how frequently they occurred. By contrast, troops in combat suffering stoppages every couple of magazines were unlikely to find this acceptable even if these were technically ‘minor’ incidents that did not affect the reliability target.
The MRBF calculation also led to a certain amount of manipulation as the LSW struggled to meet the reliability target. For instance, a fractured bolt was initially classified as a ‘critical’ failure. If a spare bolt was included in the tool wallet, however, the same incident immediately became something the user could theoretically rectify – no matter how unlikely in practice – and thus became merely a ‘serious’ incident which did not count toward the MRBF. Artificial as this may be, it is exactly what was recommended, and a complete replacement bolt was added to the LSW tool wallet for the trials. Once the MRBF target had been met, however, the standard contents of the wallet were quietly revised – and the spare bolt disappeared before issue.
The IW initially achieved an MRBF figure of 1,250, but this was ‘corrected’ to 2,500 by ignoring ‘critical’ failures caused by issues the design team believed could be eliminated by design changes before production; a rather optimistic way of conducting reliability trials. The LSW scored significantly better – 2,713 for rounds from an open bolt and 4,746 for shots from a closed bolt – but still fell well short of the target figure, even after correction. Both weapons were found to be very accurate in single-shot mode; but while the first round on automatic was generally on target, subsequent rounds were well off-target, particularly at longer range. This was inevitable to some extent, as muzzle climb on automatic will always push the weapon off-target. The effect was more severe than expected, however, especially for the LSW where the bipod should have stabilized the weapon. Rounds also started ‘cooking off’ after firing about 330 rounds at a rate of one per second – well above the rate at which a rifle would be fired, but not above that expected of a machine gun. Other problems included issues with the bipod catch and cracking of the bolt carriers.
The SA80 system was also assessed by the Army’s Infantry Trial & Development Unit (ITDU), in parallel with the Ordnance Board trials. The ITDU trials were not intended to assess reliability – that would be tested by the Ordnance Board – but to assess usability and effectiveness. For instance, the ITDU expressed concern that the LSW did not meet the requirement to deliver effective suppressive fire. Despite this, its final report indicated that ‘the IW proved itself to be a robust and reliable weapon that suffered few stoppages… the majority of the problems previously noted have now been overcome’ (quoted in Raw 2003: 85).
THE XL85 AND XL86 SERIES
During the trials, the XL70-series weapons were replaced by the XL85E1 IW and XL86E1 LSW. These would effectively be the production build standard, and incorporated a number of changes. Only right-handed versions of both weapons were produced, the requirement for a left-handed version having been effectively dropped – a conversion kit was promised, but never materialized. The RSAF final report noted that the required MRBF for the LSW had still not been met, though the design team remained optimistic that this could be achieved. Overall, the acceptance meeting agreed to adopt the IW, and give limited approval for production of an initial tranche of 30,000 weapons. Concerns remained over the LSW’s accuracy on automatic and its ability to deliver a sufficient weight of suppressive fire, however. Its adoption was therefore deferred until these issues could be resolved.
Deferring adoption of the LSW gave the Army significant problems. The remaining L4A4 Light Machine Guns could not be kept in service indefinitely, as stocks of spare parts were exhausted; and retaining the GPMG at section level would necessitate significant purchases to replace existing worn-out weapons. It would also mean that infantry sections would need both 5.56mm ammunition for the IWs and 7.62mm ammunition for GPMGs, thus complicating logistics.
Going back to the drawing board to design a new LSW that might meet the specifications more closely was not a serious option; it would take several years to develop a new weapon, and there was no guarantee that it would perform any better than the existing LSW. The preferred option was to allow RSAF Enfield a limited amount of time to rectify the problems. Meanwhile, the MoD would define subjective criteria (such as providing ‘effective suppressive fire’) more clearly, and indicate the minimum performance they would accept. Although this would require some compromise, the thinking was that this might be the best outcome for the Army if successful, as it retained the advantages of the original plan.