The Ultimax 100 light machine gun had been developed by ST Kinetics/Chartered Industries of Singapore company and is in service with Singapore Armed Forces and in some other countries.
The Ultimax is a very lightweight and mobile support weapon. It is a gas operated, rotating bolt locked, full automatic only, magazine fed firearm, that fires from open bolt. The gas system has 3 positions gas regulator. The overall action design allows the bolt carrier/bolt group to travel all the way back without being stuck into the rear of the receiver. This feature helps to reduce felt recoil and to improve accuracy. Original Ultimax 100 (early model) had fixed, heavy, air cooled barrel; Current version, Ultimax Mk.3, has quick detachable barrels, available in two lenghts: standard of 508 mm (20 inches) and short of 330 mm (13 inches). The buttstock is also quick detachable, and due to light weight and relatively low recoil, Ultimax can be fired off hands, with buttstock removed, thus making it suitable for close combat and urban operations. However, the accuracy without use of buttstock is marginal, to say the best. The Ultimax can be fed from proprietary, drum type magazine for 100 rounds each, or from STANAG-compatible (M16-type) box magazines for 20 or 30 rounds. The 100 rounds magazines are great for sustained fire, but can be reloaded only with the help of the magazine loading tools, due to powerful springs.