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The caseless propellant of the weapon is fundamentally based on the Lightweight Small Arms Technologies (LSAT) program, which was intended at it's core to provide lighter, yet still as or more reliable and capable platforms, for infantry as possible. The caseless propellant combines aspects of this design, with metal storm, or a caseless propellant that was intended to be set off via electricity, in much the same manner (similiar to the VEC-91). The primary advantage of caseless rounds is their reduced weight, in that removing a brass casing helps to reduce the weight of the overall cartridge. For many cartridges, the brass casing can be nearly half the weight of the overall round. For instance, for a 5.56mm, the bullet is roughly 4.1 grams, the propellant (or gunpowder) is 2 grams, and the brass casing is approximately 6+ grams, which leads to about a 12.3 gram overall cartridge. If just the weight of the round and propellant are considered, than the overall required weight for the bullet to function is only 6.1 grams, which is about half the weight the standard 5.56mm cartridge. This means twice as much ammunition can be carried for the same weight, which has substantial benefits in regards to logistics and sustained combat; on the other hand, heavier less practical ammunition, such as the 7.62mm x 51mm NATO, would be nearly the same weight as the 5.56mm, or 12.4 grams (for 2.7 grams for the powder and 9.7 grams for the bullet), allowing it to reduce the weight of the overall system substantially, or put it to the same levels as the 5.56mm. In addition to this, with less mass of the reciprocating parts, the recoil can be reduced substantially. The primary issue with such cartridges however is their increased heat sensitivity and chamber pressure. Because the brass or casing does not absorb both the heat and expanding force of the propellant, the cases are more susceptible to cook offs, or being detonated by accident via increased heat in the chamber. The goal of caseless weapon's, therefore, is to reduce the heat sensitivity of the cartridges, decrease the pressure, or produce a chamber that can handle the increased pressure or heat. Caseless weapons also need an additional seal to seal off the propellant, to act as a virtual casing, attached to the bolt and firing pin.

Based on the original G11 program, the LSAT ammunition was intended to replicate the heat insensitive binder developed by Dynamit Nobel, the founder of the nobel foundation, and responsible for the development of shock insensitive explosives, such as dynamite. Premature ignition of ammunition from heat in the chamber, known as cook-off, was a major problem with early prototypes of the G11 where synthetically bound nitrocellulose, formed into blocks, was used. Normally, when a bullet is fed into a chamber its case insulates the propellant from igniting until its impact-sensitive primer is struck by a firing pin or striker. The case aids in insulating the propellant from the heat of the chamber and it takes time for the temperature to rise sufficiently, inside a chambered round, to ignite the propellant. In addition, extracting a hot case removes heat from the system. As a result of doing away with traditional cases, the G11 became a safety hazard and had to be withdrawn from the 1979 NATO trials. The high rate of fire and lack of cartridge cases made cooking-off a significant problem since the heat buildup in the G11 chamber was immense, due to the chamber having no provision for cooling, as with a reciprocating bolt system which allows hot air to leave the chamber when the bolt is retracted and the chamber is exposed to air. The vertically swivelling chamber furthermore made gas sealing at each end at such high pressures impractical, as opposed to a cross-sectional round-inside-round bolt-to-chamber fit with appropriate gas sealing . To solve this, Heckler and Koch formed a partnership with Dynamit Nobel who redesigned the cartridge to use a new High Ignition Temperature Propellant (HITP). The cook-off problem was reduced, by using a denatured HMX propellant with a special binder and coating for the ammunition that increased the spontaneous ignition temperature by another 100 °C above that of standard, nitrocellulose (180 °C) propellant.

While the G36 was eventually chosen over the G11 due to it's reduced complexity and cost, future designers of the LSAT sought to replicate this heat insensitive binder. 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 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), in some of it's weapon designs. The High Ignition Temperature Propellant (HITP) was created by Nobel by using a denatured HMX propellant with a special binder and coating for the ammunition that increased the spontaneous ignition temperature by another 100 °C above that of standard, nitrocellulose (180 °C) propellant, which made it far less susceptible to cook offs.

While the program intends to expand into a variety of other cartridges, notably one which mimics the 6.5mm grendel, fundamentally this type of ammunition can be applied to nearly type of cartridge. All that is required is to combine the bullet with the newer propellant and binder, and adapt the gun to possess the seal necessary for firing each round. This makes it applicable ot a wide variety of potential firearms, including pistols, rifles, and machine guns. The 5.56mm and 7.62mm are already in development, while plans for future cartridges exist, as well.



Metal Storm
Metal Storm used the concept of superposed load; multiple projectiles loaded nose to tail in a single gun barrel with propellant packed between them. The Roman candle, a traditional firework design, employs the same basic concept, however, the propellant continues to burn in the Roman candle's barrel, igniting the charge behind the subsequent projectile. The process is repeated by each charge in turn, ensuring that all projectiles in the barrel are discharged sequentially from the single ignition. Various methods of separately firing each propellant package behind stacked projectiles have been proposed which would allow a "single shot" capability more suitable to firearms. J. Mike O'Dwyer, an Australian inventor, observed that these methods did not eliminate the problem of unintended propellant ignition caused by hot gases "leaking" back up the barrel. J. Mike O'Dwyer's original Metal Storm patents demonstrated a method whereby projectiles placed in series along the length of a barrel could be fired sequentially and selectively without the danger associated with unintended propellant ignition.

In the original Metal Storm patents, the propellant immediately behind the projectile closest to the muzzle of the gun barrel was ignited by an electronically fired primer, the projectile was set in motion, and at the same time a reactive force acted on the remaining stacked projectiles in the barrel, pushing them backwards. By design, the remaining projectiles would distort under this load, expanding radially against the gun barrel wall. This created a seal, which prevented the hot propellant gases (expanding behind the lead projectile) prematurely igniting the remaining propellant charges in the barrel (blow-back). As each of these propellant charges was selectively (electronically) ignited, the force "unlocked" the projectile in front and propelled it down the gun barrel, and reinforced the radial expansion (and hence the seal) between the projectiles remaining in the barrel and the barrel wall. Subsequent designs discarded the "distorting shell sealing against the barrel" concept in favor of containing the propellant in "skirts" that form the rear part of each projectile. These skirted projectiles differ from conventional shells and cartridge units in that the skirts are part of the projectile, and in that the skirts are open-ended (at the rear). The rearward seal to the skirt is provided by the nose of the following projectile in the barrel. As in the previous design, the firing of a projectile results in a rearward impulse on the remaining projectiles stacked in the barrel. This results in the skirts of the remaining shells in the barrel being compressed against the following shell heads, effectively creating a seal that prevents hot gases in the barrel triggering unintended propellant ignition ("blow-back" ) along the length of the barrel. Metal Storm also introduced inductive electronic ignition of the propellant, effectively from outside the barrel.

Despite not possessing all of these attributes, the caseless powder does borrow elements from the metal storm powder, most importantly the electrically ignited propellant. Not only does this reduce the sensitivity of the propellant (being ignited by electricity, instead of kinetic energy), but it also allows it's use in a variety of different weapons. Like in the 3GL, the weapon can be ignited by utilizing electricity.