LSAT Light Machine Gun - Design

Design

The LMGs built made a 44% and 43% reduction of weight (for the cased telescoped and the caseless weapons, respectively). 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 standard LSAT machine gun weighs 9.4 lb empty, compared to 17.6 lb for a standard SAW. Cased telescoped ammunition weighs 40% less than brass cased ammo, so a 100 round ammunition belt weighs about 2 lb for the LSAT, compared to 3.3 lb for a brass cased belt.

The LMG design is a traditionally laid-out machine-gun. It has several features conducive to its use as a light machine gun, such as a quick-change barrel, a vented fore-grip, a belt feeding mechanism, provisions for the use of an ammunition pouch, and a rpm rate of fire of approximately 600 RPM. Other features include its light weight, an ammunition counter, and a highly stiff and heat resistant barrel achieved with the use of fluting and specialized alloys. When firing, the weapon's 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, accounting for the slightly increased weight of the caseless version.