Lightweight Small Arms Technologies

The Lightweight Small Arms Technologies (LSAT) program is funded by the U.S. Joint Service Small Arms Program, with the goal of significantly reducing the weight of small arms and their ammunition.

Initiated in 2004 (then called the Lightweight Machine Gun and Ammunition program), development is now led by Textron. Development began with two types of weight reducing ammunition, and a light machine gun to serve as a testbed and technology demonstrator.

In 2008, the program had achieved working prototypes for the polymer-cased ammunition and the LMG, which were tested by the Army in 2012.

After further research and development into both ammunition types and the weapons that fire them, one of the two shall be chosen for production.

Background

The Lightweight Small Arms Technologies program is the culmination of much research and information obtained by the US Army. It succeeds several other programs to develop new small arms technologies, each program of which produced results that were infeasible or insignificant. The first three (the Special Purpose Individual Weapon, the Future Rifle Program, and the Advanced Combat Rifle program) demonstrated the ballistic problems of flechette ammunition, and the ACR program also showed the inability of kinetic-energy firearms to significantly compensate for human inaccuracy (the small accuracy increase of all of the concepts tested was out-weighed by the trade-offs required). The subsequent identification of programmable air-bursting munitions as the only way to significantly increase accuracy was followed by the fourth, and most recent, cancelled program—the OICW program. The ability to detonate an explosive in the air at range provided a huge increase in accuracy, but the resultant XM29 proved too heavy to use. The separation of the XM29 into the XM25 and the XM8 provided no long-term solution to the weight problem, and the program was suspended indefinitely. Developments in lighter weapons (such as LSAT) could see a return to the concept, although the military has not recently expressed a desire for a return. The indefinite suspension of the program sounded the death of short-term advances in infantry weapon lethality, and indicated the shift to other projects.

After the failure to significantly improve firearms of the near future, the U.S. military is using the development of other infantry equipment to improve the effectiveness of the soldier. Most notable is the development of electronics and information technology to advance soldiers' awareness and communications (as with the Land Warrior program). However, this new equipment increases the weight burden on the soldier, who then has to strike a compromise between the extra equipment and mobility. Reducing the weight of infantry equipment allows for more mobile, better equipped troops. Since a soldier's weapon and ammunition are a large portion of his total burden (and available technologies exist to sharply lighten them), reducing the weight of the two is crucial to increasing the amount of advanced technology a soldier can carry.

The LSAT program allows a vast reduction in soldiers' carrying loads, thereby allowing new and more equipment, reducing logistical strain, and increasing mobility. The combined benefits to soldier effectiveness are big enough to warrant the investment in the new lightweight technologies.

Technologies

The existence of weight-reducing technologies made the LSAT program feasible, and many of these technologies can be seen in the program's products. The lightest existing ammunition to fire standard bullets comprised caseless varieties. The Heckler & Koch G11 was the only weapon to achieve a service capable assault rifle firing caseless ammunition. Its unique ammunition, designed by Dynamit Nobel, introduced several important innovations, such as improved internal ballistics through the use of a primer, and the prevention of cooking off (the lack of a case makes it easier for a hot chamber to ignite the exposed propellant) through the use of the less sensitive hexogen/octogen

Polymer casing for ammunition had already been developed and produced,

Further budding technologies, such as alternative barrel materials (such as ceramics), and the increased efficiency and size reduction of telescoped ammunition (used by the G11 and other developmental weapons), also formed the basis for the LSAT program.

Program

In 2004, the Joint Service Small Arms Program created the Lightweight Machine Gun and Ammunition program to compare conceptual, lightweight machine guns and ammunition designs by two teams of companies. The team of eight, led by AAI Corporation had their design chosen over the design of the General Dynamics-led team. In 2005, the project was replaced with the Lightweight Small Arms Technologies program to place the emphasis on developing technologies for a wide range of small arms. The earlier Lightweight Family of Weapons and Ammunition concept is visible in the new program. The cohesive team of companies is combined with government support to ensure success.

In accordance with the program's name, the focus is on creating lightweight technologies for all small arms, and the Light Machine Gun it has started with is an entry point for a family of lightweight small arms and ammunition. Beginning with an LMG is unusual for an effort to develop a new family of weapons, although the increased engineering difficulty of a machine gun over a rifle is balanced against decreased attention and antagonistic scrutiny. The program minimized development risk: it used G11 technology that had been on the verge of deployment; and the parallel development of the composite-cased and caseless ammunition meant that, if the caseless ammunition effort succeeded, much of the development work gained with the composite cased weapon could be applied to it, and, if it failed, the composite-cased version was likely to succeed on its own.

The LSAT program uses a 'clean slate' design and had no requirements imposed on abiding by contemporary ammunition and weapon standards. Despite this, the program is using the M855 5.56×45mm round to provide comparison with existing weapons. The program has listed scalability of the ammunition calibre as a requirement, and its pursuit of a very light company machine gun would require a larger round. Therefore, the program seems set towards a more accurate, harder-hitting round (such as the 6.5 mm Grendel or 6.8mm Remington SPC).

The program has set itself weight reduction goals over the existing M249 and its ammunition of 35% for the weapon and 40% for the ammunition. Further goals to improve battlefield effectiveness have also been set: improved lethality; improved controllability (through recoil reduction, etc.); improved ergonomics; improved reliability and maintainability; integration of electronics; and equivalent cost and producibility to the existing weapon and ammunition.

Achievements

By 2008, the program had made tremendous progress, with all of its goals either fully achieved or with strong potential for achievement.

Light machine gun

The LMGs built made a 47% and 43% reduction of weight for the caseless weapon and cased telescoped weapons, respectively. The more complex chamber-sealing mechanism of the caseless weapon somewhat increases its weight compared to the composite-cased weapon. Secondary goals have also been met: the LMG has the potential to improve battlefield effectiveness (due to its simpler and more consistent weapon action, its light weight and low recoil, and its stiffer barrel); its use of recoil compensation (with a long-stroke gas-system, for example) has produced positive feedback regarding controllability; the simpler mechanism of the LMG is both more reliable and easier to maintain; a rounds counter has been integrated to improve maintainability, and the weapon is capable of accepting other electronic devices; improved materials used in the chamber and barrel have reduced heat load on the weapon; and the weapon cost is equivalent to the existing M249.

The LMG design is a traditionally (non-bullpup) laid-out machine-gun. It has many of the capabilities of other light machine guns, such as a quick-change barrel, a vented fore-grip, belt-fed ammunition, an ammunition pouch, and a roughly 600 rpm rate of fire. New features include the unique weight of 9.2 pounds for CT and 9.9 pounds for CL,

Assault rifle

Design of an LSAT battle rifle began in 2008.

Ammunition

The cylindrical shape of the ammunition is crucial to the weapon's straight-through feed-and-ejection system, and it is the similar shape of the cased-telescoped ammunition to the caseless-telescoped ammunition that allows the parallel development of the two weapon systems. Telescoped ammunition's most notable benefits include the greater propulsive effectiveness of a telescoped round over standard ammunition, and the shorter feed and action times allowed by the shorter length of a telescoped round (both the cased and caseless designs are roughly 30% shorter). If the weapon and ammunition prove superior to existing weapons, a new caliber may be chosen. An intermediate round with characteristics similar to the 6.5 mm Creedmoor is being considered along with the possibility of using a common round in more roles including GPMG and marksman weapons.

The cased ammunition is more advanced in development, partially due to the fewer technical difficulties and the fewer differences with standard ammunition. It has already reached the required technology readiness level of 5. As of 2008, the cased ammunition has been tested for a wide range of operating temperatures, and it has had over 9000 rounds fired (approximately 6500 rounds of Spiral 1 ammunition, and over 2000 of Spiral 2). The second spiral version of the cased ammunition produced a 33% weight reduction (falling just short of the program goal), while the ongoing development of the third spiral of cased ammunition has achieved a roughly 40% reduction. The third spiral is also 30% smaller than standard ammunition. The improvement by the third spiral of cased ammunition over the second spiral was achieved partially by compacting and consolidating the propellant (thereby allowing a smaller cartridge case and round). Having reached a sufficient technology readiness level, the Spiral 2 ammunition is being prepared for a contracted 2000 round delivery. The cased ammunition has shown itself as a virtually risk free option, with present and potential ability grounded in success. In addition, development of the cased ammunition firing weapon has significantly improved understanding of the weapon action and requirements. Cased telescoped ammunition for the LSAT light machine gun reached technology readiness level 7 after 25,000 rounds were fired in trials in 2011.