The U.S. Marine Corps and U.S. Army agree they may have finally found a caseless ammunition design that will work reliably in combat and be much (37 percent) lighter than conventional 5.56mm ammo. Caseless ammo is not a new concept but you need the right materials and right design to make it work. It’s all a matter of getting the right tech and the right design. Back in the 1980s the German firm Dynamit Nobel developed a 4.73mm round that weighed much less than the existing 5.56mm rounds but was similar in effectiveness. The new (at the time) G11 assault rifle was designed to fire the caseless 4.73mm round. A G11, along with 510 rounds, weighed the same (7.36 kg/16.2 pounds) as an M-16 with 240 rounds (eight, 30 round magazines.) The West German army tested the G11 extensively in the late 1980s and was considering adopting it and its caseless ammo to replace its 7.62mm assault rifles. But then the Cold War ended, Germany was united, and the decision was made to go with the cheaper G36 5.56mm weapon. The caseless ammo was also more expensive than the conventional 5.56mm stuff, and there were still concerns about reliability, even after years of testing. Not much work was done on this caseless ammo in the 1990s but after 2001 American firms began working on upgrading and improving the Dynamit Nobel tech and field testing has shown that the new polymer case design is safe and reliable. But the new caseless design has to survive combat testing and the military has yet to decide on when and where to carry that out.

Meanwhile the U.S. Army completed development of a new LSAT (Lightweight Small Arms Technology) 5.56mm machine-gun in 2012. But this new machine-gun was tested using two types of lightweight ammo and it wasn’t until now that one of those lightweight ammo designs reached the point where it was ready for combat testing. The LSAT machine-gun weighs 4.27 kg (9.4 pounds) compared to 8 kg for the current M249. Moreover, the ammo for the new machine-gun is 37 percent lighter as well. Thus the new machine-gun, with 1,000 rounds of ammo, weighs 13.9 kg (30.6 pounds), which is 40 percent less than an M249 with a thousand rounds. Moreover, the new ammo takes up twelve percent less space. Developers are working on caseless 5.56mm ammo that will take up 40 percent less space.

The U.S. Army came up with a radical new machine-gun design in 2006, mainly to save weight. The U.S. Army is really making an effort to reduce the load the infantry have to carry into combat. In both Iraq and Afghanistan infantry did most of the fighting, and the troops are using the Internet to hammer the brass and politicians about the excessive loads they have to carry.

In the beginning the army called together some of its small arms manufacturers, gave them some money, and told them to come up with a much lighter 5.56mm light machine-gun. In effect, replace the M249 with the LSAT. “Start from scratch” the weapons wonks were told. The only constant were the caliber of the weapon (5.56mm) and the troop handling of the LSAT should be roughly the same as the M249. The goal was to greatly reduce the 17.41 kg (38.3 pounds) the M249, and 600 rounds of ammo, weighs. This is what a machine-gun armed soldier usually has to carry into combat.

Starting in 2008 the LSAT was developed, built, and tested. LSAT passed its first field tests in 2012 which involved having eight prototypes firing 25,000 rounds over three weeks. At that point everyone agreed that it works. More testing was required to ensure ruggedness and reliability. That took five years, about twice as long as expected.

The LSAT actually comes in two versions. One uses ammo using a non-metal, telescoped case, and the other uses caseless ammo. The telescoped ammo is ready for use now while the caseless stuff was still in development. Both LSAT weapons feature a revolutionary ammo feed that employs a pivot, rather than a bolt, to load the ammo into the chamber. This design propels the case out the front of the weapon. Naturally the caseless ammo has no case to eject. The use of the pivot reduces overheating problems, which are more of a hassle with the plastic case of non-metal telescoped cartridge prototype (which is a straight case, like a pistol, not a bottleneck case more common with high powered rifles). The caseless round is the ideal solution but this design is more difficult to manufacture. Caseless rounds have been developed before but were found to be more expensive and more vulnerable to rough handling. The original LSAT expectation was that if the caseless round were used, the LSAT and 600 rounds would be 9 kg (19.9 pounds) lighter than the current M249 and its ammo. The new plastic case and the LSAT is 6.8 kg (15 pounds) less than the M249.

In early 2012 eight LSAT machine-guns and 100,000 rounds of the telescoped ammo were delivered for army troops to actually use and passed field tests. At this point it became possible to use the same technology for a new assault rifle. While LSAT passed muster with the troops and the realities of use in a combat zone by 2012 most of the fighting was over. The new machine-gun will be much appreciated by infantry operating in Afghanistan, where the machine-gunner is often lugging his weapon and all that ammo up steep hills. But back home there was less enthusiasm, and money, for a new generation of assault rifle and light machine-gun.