How a Ultimax 100 LMG Works

Wikipedia: The Ultimax 100 is a Singapore-made 5.56mm light machine gun, developed by the Chartered Industries of Singapore (CIS, now ST Kinetics) by a team of engineers under the guidance of American firearms designer L. James Sullivan.[1] The weapon is extremely accurate due to its constant-recoil operating system[2] and is one of the lightest machine guns in the world.[3]

Work on a new light support weapon for the Singapore Army began in 1978. The weapon is produced by CIS (presently STK—Singapore Technologies Kinetics), initially in the Mark 1 version, later—the Mark 2, and currently, in the Mark 3 and Mark 4 variant. The Ultimax 100 (also called the U 100) is used in significant numbers by the armed forces of Singapore, Croatia and the Philippines.[1] The Mark 3 variant is currently used in the Singapore Armed Forces primarily as a support arm, and is both classified and known by soldiers as the SAW (Section Assault Weapon).

Type Light machine gun, Squad automatic weapon
Place of origin Singapore
Service history
In service 1982–present[1]
Used by See Users
Wars Bougainville Civil War
Yugoslav Wars
Anti-guerrilla operations in Indonesia & the Philippines
2006 Fijian coup d'état
Solomon Islands coup
War in Afghanistan
Sri Lankan Civil War
Production history
Designer L. James Sullivan for Chartered Industries of Singapore (CIS, now ST Kinetics)
Designed 1978[1]
Manufacturer • CIS: 1982–2000[1]
• ST Kinetics: 2000–present[1]
Produced 1982–present[1]
No. built ~80,000[1]
Variants See variants
Specifications
Mass • Mark 2: 4.75 kg (10.47 lb)[1]
• Mark 3: 4.90 kg (10.8 lb)[1]
• 6.8 kg (15 lb) when loaded 100 rounds
Length • Mark 2: 1,030 mm (40.6 in) with buttstock, 800 mm (31.5 in) w/o buttstock[1]
• Mark 3: 1,024 mm (40.3 in) with buttstock, 810 mm (31.9 in) w/o buttstock[1]
Barrel length • Standard: 508 mm (20.0 in)[1]
• Ultimax 100 para: 330 mm (13.0 in)[1]
Cartridge 5.56×45mm NATO[1]
Caliber 5.56 mm (0.22 in)[1]
Barrels Single barrel (progressive RH parabolic twist, 6 grooves)[1]
Action Gas-operated, rotating bolt[1]
Rate of fire 400–600 rounds/min[1]
Muzzle velocity 970 m/s (3,182 ft/s) (M193 cartridge)
945 m/s (3,100.4 ft/s) (SS109/M855 cartridge)
Effective firing range 100–1,200 m sight adjustments[1]
Maximum firing range 460 m (M193 cartridge)
1,300 m (SS109/M855 cartridge)
Feed system 100-round drum magazine or 30-round STANAG M16 box magazine[1]
Sights Rear aperture sight and front post
472 mm (18.6 in) sight radius[1]