STK Ultimax 100
Summary
| Country | 🇸🇬 Singapore |
| Category | Light machine gun |
| Manufacturer | ST Kinetics |
Technical specifications
| STK Ultimax 100 | |
|---|---|
| Fire Rate | 400 - 600 rounds/min. |
| Caliber | 5.56 x 45 mm OTAN |
| Magazine | drum of 100 rounds |
| Length | 1024 mm (40.3 in) |
| Weight | 4.9 kg (10.8 lb) |
| Range | 450 m (1476 ft) |
Description
The Ultimax 100 is a Singapore-made 5.56mm light machine gun developed by Chartered Industries of Singapore (CIS, now ST Kinetics) by a team under the guidance of American firearms designer L. James Sullivan. 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 variants.
The Ultimax 100 is a gas-operated automatic weapon, capable of fully automatic fire only, utilizing a short-stroke gas piston operating system. It is a locked breech weapon with a rotating bolt that contains seven locking lugs and fires from an open bolt position. The bolt contains both a spring extractor and a casing ejector. The weapon's non-reciprocating cocking handle is located on the left side of the receiver and occupies the forward position during firing. The Ultimax 100 is striker-fired and incorporates a "constant recoil" principle where the bolt carrier group travels all the way back without impacting the rear, stopping gradually against the resistance of the return springs, contributing to its low recoil. It feeds from a proprietary 100-round synthetic drum magazine, early models also used 60-round drums, or from a modified 20 or 30-round STANAG 4179 magazine. The magazine catch consists of two tapered pins on a bar controlled by the magazine release button. M16 magazines were modified by drilling two holes at the left feeding lip to allow their use. The weapon uses a manual safety mechanism, a lever on the left side of the receiver behind the trigger with settings "S" for safe and "F" for continuous fire. An internal safety mechanism secures against premature detonation. The design incorporates sheet metal stamping and the use of synthetic components. The weapon was designed to mount an M16-type bayonet and either day or night-time optics. Its ergonomics, specifically the forward grip, are described as similar to the Thompson submachine gun. The adjustable bipod is quick-detachable. The Ultimax 100 features an aperture type rear sight with range settings for distances up to 1,200 m, graduated every 100 m, placed on a sliding scale and a forward vertical post protected by two metal tabs.
The Ultimax 100 has several variants:
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Mark 1: A pre-production model with a quick-change barrel.
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Mark 2: Equipped with a fixed barrel.
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Mark 3/3A: Features a quick-change barrel and is available in two different lengths, standard and short, with an optional 10.5-inch VIP protection barrel also available. The barrel on all versions has a slotted flash suppressor and a carrying handle. The Mark 3 has a three-position gas regulator.
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Mark 4: Developed for the United States Marine Corps Infantry Automatic Rifle program and included a new fire selector module.
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Mark 5: An updated variant of the Mark 4 featuring a folding stock, Picatinny rails, and an M16 STANAG 4179 magazine well accepting 30-round box magazines and the Beta C-Mag.
STK also developed a vehicle-mounted variant. The Mark 8 variant was unveiled in 2012. The Mark 3/3A can fire both M193 and SS109/M855 cartridges depending on the barrel twist rate fitted.
The Mark 3 variant is currently used in the Singapore Armed Forces primarily as a support arm and is known as the SAW (Squad Automatic Weapon). The weapon participated in the Product Improvement Program (PIP) initiated in 1989.
The Ultimax 100 is used in significant numbers by the armed forces of Singapore, Croatia, and the Philippines. Other users include Bosnia & Herzegovina, Brunei, Chile (Chilean Marine Corps), Fiji, Indonesia (Komando Pasukan Katak, Komando Pasukan Khusus), Papua New Guinea, Peru, Serbia (SAJ), Slovenia (Specialna Enota Policije), Solomon Islands, Thailand, and the United States (Delta Force). Singapore commissioned the weapon in 1982, and it will be gradually replaced by the Colt IAR6940E-SG. It has also been used by non-state groups including the Karen National Liberation Army, New People's Army, and Tamil Tigers.