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. Following a series of military programs to investigate advances in small arms (SPIW, Future Rifle, ACR, OICW), the LSAT program is the US military's latest project to replace existing US small arms. Tactical concepts and the research from the previous small arms programs indicates that lightening small arms is the first significant step towards increasing soldiers' lethality and survivability.
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. Minimization of program risk is shown by the development of the lower performing but less risky polymer-cased ammunition alongside caseless ammunition (which falls higher in both criteria), by the use of extensive computer simulations before prototyping, and by the use of existing and proven technologies, such as the High Ignition Temperature Propellant (HITP) developed for the Heckler &amp; Koch G11.
In 2008, the program had achieved working prototypes for the polymer-cased ammunition and the LMG, which were tested by the Army in 2012. The less orthodox caseless ammunition, and a rifle firing both types of ammunition, have also been developed. The designers aim to provide further projectile improvements, including greener bullets and a more lethal caliber, as well as the use of electronics, such as rounds counters, and lasers for sighting, target acquisition, and steering.
After further research and development into both ammunition types and the weapons that fire them, one of the two shall be chosen for production. In August 2013, AAI Corporation (now Textron) was awarded a contract to continue development of both cased telescoped and caseless ammunition.
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. Computer technologies integrated into the weapon and its sights make a light weapon crucial, otherwise the soldier will have difficulty carrying the weapon and its heavy sights. Other indirect improvements in soldier effectiveness include new strategies and the development of air transport. This is aimed towards creating fast, well-equipped soldiers able to be quickly deployed to counter threats. The logistics and mobility problems of heavy equipment hinder this possibility.
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 &amp; 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 as the explosive component. The Advanced Combat Rifle experimental program gave the US Army access to the ammunition and entrenched the ammunition as a viable option. With the high efficiency and lethality of the ammunition, the vast expenditure such a concept had needed for development, and the reduced risk of using an already proven ammunition design, the LSAT program chose a licensed version of Dynamit Nobel's caseless ammunition as a route towards its goal of weight reduction. The LSAT program also uses the same concept of a rotating chamber as the G11 (albeit, the LSAT LMG chamber swings around a longitudinal pivot. whereas the G11 chamber rotated around a horizontal axis at its very centre).
Polymer casing for ammunition had already been developed and produced, and it provided the second route for achieving weight reduction. While a polymer case could never be quite as light as no case, the risks involved in the use of polymer ammunition were less, due to its similarity to present ammunition and the reduced heat load on both the weapon and the ammunition's propellant.
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. This parallel development involves using what is essentially the same weapon for both types of ammunition, with the same action (having only marginal differences, such as added chamber sealing technologies required for the caseless firing version) and the same weight-lowering technologies. The program uses extensive computer simulation and modelling, particularly of the weapon action. This reduces both time and expenditure for prototyping and testing. The program also uses a 'spiral development' approach, whereby the weapon and ammunition is rolled out in stages or 'spirals', each stage producing a new version that is an improvement on those from previous spirals.
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, a rounds counter, and a highly stiff and heat resistant barrel achieved with fluting and special materials. Possibly the most radical part is its firing action: the weapon uses a swinging chamber. The chamber swings around a longitudinal pivot; it swings from horizontally parallel with the pivot (the firing position), to vertically parallel (the feed position), and back again. A long-stroke gas-piston is used to operate this action. A round is fed into the chamber at the feed position using a rammer, and the new round also serves to push a spent or dud round out of the far end of the chamber. Such rounds are pushed forward, parallel to the barrel, and they slide into a separate mechanism that ejects them out of one side of the gun. The advantages of this whole action include its simplicity, its isolation of the chamber from barrel heat, and its positive control of round movement from extraction to ejection. In the caseless firing version of the weapon, another mechanism is introduced to seal the chamber during firing (which is why the caseless weapon is heavier).
Assault rifle.
Design of an LSAT battle rifle began in 2008. Halfway into 2008, the designs are nearing completion. The rifle designs are made to use the same cartridge as developed for the LMG, and this means separate rifles are being designed for the cased and caseless cartridges. Design began with seventeen concepts; after the concepts were investigated and trade-offs were analysed, only two remained for the